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CLass 8 Physics Chapter 1 to 6

Exercise

24 Qs

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Which is true for a wave? (here n = frequency, T = time period).

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In the region of compression in longitudinal wave, the density of the medium

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The linear distance between the compression and the adjacent rarefaction is 0.8 m. The wavelength of the longitudinal wave is

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The moon is at a distance of from the earth. What is the nature of radar signal transmitted from earth?

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Wave on water surface are

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Waves inside a gas are

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A person is listening to a tone 500 Hz sitting at a distance of 450 m from the source of the sound. What is the time interval between the successive compression from the source ?

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Time period of a sound wave having the wavelength 0.2 m  and frequency 10 Hz will be

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In the following table, match the column B according to column A : 

Column (A)Column (B)
(i)Pitch(a)waveform
(ii)Quality(b)Frequency
(iii)Loudness(c)Intensity

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The depth of ocean at any place can be measured (estimated) with the help of

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When a stone is dropped in a pool of water, circular ripples are produced. These are

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Consider the following sounds: G -conversation between two girls, P-sound produced by a peacock and M-sound produced by a moving motorcycle. These sounds in the increasing order of frequency are

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Which of the following can be used to detect a flaw inside a metal block?

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The figure shows graphical representation of a sound wave. The quantities on X and Y axes respectively are

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A ripple is created in water. The amplitude at a distance of 5 cm from the point where the sound ripple was created is 4 cm. Ignoring damping, what will be the amplitude at the distance of 10 cm.

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A cathode ray oscilloscope (CRO) is a device which converts electrical signals into an active graphical representation n a fluorescent screen. The x axis is always time axis, where the 1 cm is equal to a preset time scale called time base. A sound wave is displayed on the screen of a cathode ray oscilloscope. The time base of the CRO is set at 2.5 ms/cm.
What is the frequency of the sound wave ?

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Sound waves produced by a source are propagating in a medium. The quantity/quantities that change from point to point is / are

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Which of the following statement is/are true in case of waves ?

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Speed of sound in air is 350 , fundamental frequency of an open organ pipe of 50 cm length will be

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An open pipe of length 33 cm resonates with frequency of 1000 Hz. If the speed of sound s 330 , then this frequency is 

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As an empty vessel is filled with water, its fundamental frequency

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Beats are heard due Ito interference of two sound waves. The intensity of sound changes from maximum to minimum in 100 ms. Therefore, the difference in frequencies of the two waves is

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The note "Saa" on the Sarod and the Sitar have the same pitch. The property of sound that is most importantin distinguishing between the two instruments is

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Sound waves traveling in air enters water at an angle i with the normal. It gets refracted at angle r with

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Exercise

29 Qs

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A siphon in use is demonstrated in the following figure. The density of the liquid flowing in siphon is . The pressure difference between the point P and S will be

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In a hydraulic lift, used at a service station the radius of the large and small piston are in the ratio of . What weight placed on the small piston will be sufficient to lift a car of mass ?

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Two vessels A and B of different shapes have the same base area and are filled with water up to the same height h (see figure). The force exerted by water on the base is for vessel A and for vessel B. The respective weights of the water filled in vessels are and . Then

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A buggy ABC of shape as shown in the figure is filled with water. Which of the following statements is NOT correct?

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We sit in the room with windows open. Then

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Bernoulli's principle is based on the law of conservation of :

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Action of spray-gun is based on :

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Bernoulli's equation is applicable to points :

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In a steady horizontal flow :

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In a laminar flow, the velocity of the liquid in contact with the walls of the tube is :

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The Reynolds number of a flow is the ratio of :

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Two water pipes of diameters and are connected with the main supply line. The velocity of flow of water in the pipe of diameter is :

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Water is moving with a speed of through a pipe with a cross-sectional area of . The water level gradually descends as the pipe increase in area to . The speed of flow at the lower level is :

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A tank is filled with water up to height . Water is allowed to come out of a hole P in one of the walls at a depth below the surface of water. The horizontal distance in terms of and will be expressed as :

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A fixed cylindrical vessel is filled with water up to height . A hole is bored in the wall at a depth from the free surface of water. For maximum horizontal range is equal to :

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An incompressible liquid flows through a horizontal tube as shown in the figure. Then the velocity '' of the fluid is :

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For a fluid which is flowing steadily, the level in the vertical tubes is best represented by

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There are two identical small holes on the opposite sides of a tank containing a liquid. The tank is open at the top. The difference in height between the two holes is . As the liquid comes out of the two holes, the tank will experience a net horizontal force proportional to :

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The diagram shows a cup of tea seen from above. The tea has been stirred and is now rotating without turbulence. A graph showing the speed v with which the liquid is crossing points at a distance X from 0 along a radius XO would look like

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Water flows through a frictionless duct with a cross section varying as shown in fig. Pressure at points along the axis is represented by

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A liquid flowing with speed v through a horizontal pipe of cross sectional area A enters into another pipe of double the area of cross section. Now, the speed of the liquid is

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There is a steady water flow in a horizontal tube in which, one part has cross sectional area and the other part has cross sectional area . Assume that water is incompressible. If , the ratio of the speed in part 1 and the speed in part 2, i.e. is :

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A beaker containing water is placed on the platform of a digital weighing machine. It reads . A metal body of density and mass is suspended in water in the beaker (without touching the walls of the beaker). It is attached by a suitable string fixed to some support. Now the reading of weighing machine will be

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A rubber balloon of negligible mass is filled with  of water. Its weight in water will be

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An iceberg is floating in ocean. What fraction of its volume is above the water ? (Given: density of ice and density of ocean water )

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An air bubble situated at the bottom of an open kerosene tank rises to the top surface. It is observed that at the top the volume of the bubble is thrice its initial volume. If the atmospheric pressure is 72 cm of Hg, and mercury is 17 times heavier than kerosene the depth of the tank is:

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A block of wood is floating on oil with half of its volume submerged. If the density of oil , the relative density of wood (relative to water) is:

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A rubber pipe with a diameter of 10 cm is connected to a nozzle 2 cm in diameter. Water flowing through the pipe at a speed of 0.6 ms comes out like a jet through the nozzle. The backward force of the nozzle is about:

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A spring balance A reads 2 kg with a block of mass m suspended from it. Another balance Breads 3 kg when a beaker with a liquid is put on its pan. The two balances are now so arranged that the hanging mass m is fully immersed inside the liquid in the beaker as shown in the figure. In this situation.

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Exercise

46 Qs

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When a solid object is heated, the molecules that make up the object:

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Absolute zero corresponds to :

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Iron glows in red colour when it is heated to very high temperature. The reason for this is :

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When in thermal contact, the quantity of heat lost by the hotter body is ...... the amount of heat gained by the colder body. (neglect loss of heat due to convection & radiation)

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A temperature difference of in the Fahrenheit scale will be  :

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A manufacture marks the thermometer wrongly.So At  it reads , at it reads . Then the reading at will be :

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We feel most comfortable at relative humidity at:

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2000 J of energy is needed to heat 1 kg of paraffin through . So How much energy is needed to heat 10 kg of paraffin through ?

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Ratio of thermal capacity of the body and its water equivalent is equal to:

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1 kg of water is supplied 630 kJ of energy. Specific heat of water is 4200 J/kg .So calculate the rise in temperature of 1 kg water.

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1 kg of water at is, mixed with 800 g of water at . Assuming that no heat is lost to the surroundings. Calculate the final temperature of the mixture.

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How much heat would be required to convert 14 kg of ice at  into water of ?

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Calculate the quantity of heat required to convert 10 kg of ice at to water at would be. Specific heat of water is 4200 J/kg .

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The specific heat capacity of water is 4200 J/kg . Calculate the heat capacity of 10 kg of water per :

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Bunty mixed 440 gm of ice at with 540 gm of water at in a bowl. Then what would remain after sometime in the bowl?

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For a 5 gm substance the heat supplied (in cals.) and temperature (in ) curve is given below. Then the specific heat of substance for liquid state will be :

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Ice at is put in a closed container and heat is supplied to it continuously at a uniform rate. Which of the following graphs gives the temperature variation with time correctly?

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Choose the INCORRECT statement from the following.

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A coolant in a chemical or nuclear plant is a liquid that is used to prevent different parts of a plant from getting too hot. One important property of coolant is that it :

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An Insulated vessel contains 0.4 kg of water at . A piece of 0.1 kg ice at is put into it and steam at is bubbled into it until all ice is melted and finally the contents are liquid water at . Assume that the vessel does not give or take any heat and there is no loss of matter and heat to the surroundings. Specific heat of ice is . heat of fusion of water is  heat of vaporization of water is  The amount of steam that was bubbled into the water is :

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Two identical blocks of metal are at and , respectively. The specific heat of the material of the two blocks increases with temperature. Which of the following is true about the final temperature  when the two blocks are brought into contact (assuming that no heat is lost to the surroundings)?

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A new temperature scale uses X as a unit of temperature, where the numerical value of the temperature in this scale is related to the absolute temperature T by = 3T + 300. If the specific heat of a material using this unit is 1400 J its specific heat in the S.1. system of units is :

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A certain amount of heat is required to raise the temperature of x gram of a substance through . The same amount of heat when taken away from y gram of water, it cools through . Therefore, the specific heat of the substance is 

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10 g of ice at is added to 10g of water at . What is the final temperature and amount of ice left in the system ?(System is kept inside an ideal insulator)

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The quantity/ quantities that does/do not have mass in its/their dimensions is/are

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The superficial expansion of a metal is and volume expansion is , then :

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If represent linear expansion, represent superficial expansion and represent cubical expansion, then choose the correct statement :

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Expansion in a substance is :

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is coefficient of real expansion of a liquid, is coefficient of apparent expansion of a liquid and is coefficient of cubical expansion of the container then the correct relation is :

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Per  is unit of:

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Clock's pendulum is made of invar because:

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Which of the following  curve represent variation of  density of water with temperature best:

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If represent the absolute temperature of an ideal gas, the volume coefficient of thermal expansion at constant pressure, is :

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A wire of length 1 cm and a cube of side 1 cm of the same metal are heated through 1 If the change in length of the wire is x cm then the change in volume of the cube is :

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The temperature of a metal coin is increased by and its diameter increases by 0.15%. Its area increases by nearly:

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An aluminium measuring tape which is correct at measures the length of a line as 80 cm at . If thermal coefficient of linear expansion of aluminium is of  the correct length of the line is

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Two identical beakers with negligible thermal expansion are filled with water to the same level at . If one say A is heated while the other one is cooled, then:

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Zeroth law of thermodynamic signifies:

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The lengths and radii of two rods made of same material are in the ratios 1 : 2 and 2 : 3 respectively ; If the temperature difference between the ends for the two rods be the same, then in the steady state, the amount of heat flowing per second through them will be in the ratio:

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Five rods of same dimensions are arranged as shown in the fig.They have thermal conductivities, and  when points A and B are maintained at different temperatures. No heat flows through the central rod if:

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If heat is supplied to the system it :

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Two rods having length and made of materials with the linear expansion coefficient and were soldered together. The equivalent coefficients of linear expansion for the obtained rod:

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The nature of the graph of pressure P against reciprocal of volume V of an ideal gas at constant temperature

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A solid cube and a solid sphere of identical material and equal masses are heated to the same temperature and left to cool in the same surroundings. Then:

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The following three objects (1) a metal tray, (2) a block of wood, and (3) a wooden cap are left in a closed room overnight. Next day the temperature of each is recorded as and respectively. The likely situation is :

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We are able to squeeze snow and make balls out of it because of : 

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Exercise

60 Qs

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Two mirrors are inclined at an angle , an object is placed asymmetrically between them. Then number of images formed will be:

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An object A is placed at a distance 'd' in front of a plane mirror. If one stand s directly behind the object at distance 's' from the mirror, then the distance of the image of A from the individual is

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The linear magnification for a mirror is the ratio of the size of the image to the size of the object, and is denoted by . Then we may write: (symbols have their usual meanings)

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The angle beyond which when a ray is incident, it is completely reflected back is called :

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Which of the following conditions are necessary for total internal reflection to take place at the boundary of two optical media ?
1. Light is passing from optically denser medium to optically rarer medium.
2. Light is passing from optically rarer medium to optically denser medium.
3.Angle of incidence is greater than the critical angle. 
4.Angle of incidence is less than the critical angle.

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For total internal reflection, rays of light must go from:

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To get 9 multiple images the angle between the plane mirrors should be:

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In a room lighted by an electric bulb, it is found that the shadow of the ceiling fan hung in the centre is falling on a wall opposite to the door. What can you say about the position of the bulb?

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When a ray of light strikes a plane mirror at an angle of with the mirror, what will be the angle through Which the ray gets deviated?

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A light ray falls on a mirror and deviates by , then the angle of reflection will be

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A boy runs towards a convex mirror with a speed v. His image is seen to move towards the mirror at a speed v'. Then,

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An object is placed in front of a concave mirror focal length f. An erect image is formed with a magnification of 2. To obtain real image with the same magnification, the object has to be moved through a distance of

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A girl standing in front of a vertical plane mirror, is able to see herself only upto her knees. She can see the lower part of her legs, if :

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Image of an object in a concave mirror is observed on a screen first by keeping the object at position A and then at another position B. The magnifications in the two cases were determined. If , then

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Light incident on a rotating mirror M is returned to a fixed mirror N placed away from M. The fixed mirror reflects it back to M (along the same path) which in turn reflects the light again along a direction that makes an angle of with the incident direction. The speed of rotation of the mirror is:

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Which of the following phenomena can be demonstrated by light, but not with sound waves in an air column?

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An object is place at a distance from the focus of a concave mirror. Its real image is formed at a distance  from the focus. Hence, the focal length of the mirror is

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The focal length of eye lens and object lens of a telescope is 4 mm and 4 cm respectively. lf final image of an far object is at  . Then the magnifying power and length of the tube are

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A compound microscope has an objective of focal length 1 cm and an eyepiece of 4 cm. If the tube length is 20 cm. Then the magnification of the compound microscope is : (final image is at D )

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The radius of curvature of the convex surface of a planoconvex lens is 10 cm. What is the focal length of the plano-convex lens? (Here )

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Two identical plano-convex lenses can be combined in three ways, as shown. The ratio of the focal lengths of these combinations will be

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If red and violet colour are passing through same glass sheet simultaneously then relation between their velocity will be

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When light is incident on the interface of glass and air as shown in the figure, the green light is just totally internally reflected. Then the emerging ray in air contains :

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If the central portion of a convex lens is wrapped in black paper as shown in the figure

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A ray of light incident at an angle on the boundary separating two transparent media. It is transmitted. When angle is increased very slightly (by negligible amount), the ray suffers a total internal reflection. The difference between the angles of deviation in two cases is

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The figure shows positions of object O and its diminished image I. This is possible if 

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A convex lens of focal length f is cut into two halves as shown. Light rays parallel to the principal axis are incident on one half of the lens (say This will form an image at

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Consider a ray light passing through a rectangular glass slab. Let the emergent ray shift laterally by a distance .The shift depends on

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Critical angle for glass is and that for water is The critical angle  at the water glass interface is such that

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As planets are much closer to the Earth than the stars,

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In the figure shown below. A, B, C are points on the principal axis of a spherical mirror / lens. Which of the following arrangements will produce image of the object ?

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An object is placed 0.40 m from one of the two lenses of focal lengths 0.20 m and 0.10 m respectively as depicted in the figure. The separation between the lenses is 0.30 m.
The final image formed by this two lens system is at

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A ray of light enters a slab of material with increasing refractive index. Four possibilities of the trajectory of the ray are shown below.
The correct choice is:

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A light source is placed away from a screen. A converging lens placed at a certain position between the source and the screen focuses the image of the source on the screen. The lens is moved a distance of and it is found that it again focuses the image of the source on the screen. The focal length of the lens is

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In the figure below a ray of light travelling in a medium of refractive index passes through two different connected rectangular blocks of refractive indices .
The angle of incidence is increased slightly, Then angle

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Which of the following does not represent correct refraction?

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How much water should be filled in a container 21 cm in height, so that it appears half filled when viewed from the top of the container?
[refractive index of water = ]

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A student sees the top edge and the bottom centre C of a pool simultaneously from an angle above the horizontal as shown in the figure. The refractive index of water which fills up to the top edge of the pool is 4/3. If h/x = 7/4 then cos is

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A convex lens is used to form an image of an object on a screen. If the upper half of the lens is blackened so that it becomes opaque. Then

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The middle colour in sunlight spectrum is

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A ray of light on a prism having one silvered surface, at an incident angle of as shown in figure. After refraction and reflection it retraces the path, then the refractive index of prism material is (prism angle is )

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Find the value of for the case shown in figure

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A rainbow has circular shape because :

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Dispersion of white light into its constituent colours occurs during

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A ray of light passing through an equilateral triangular prism gets deviated at least by . Then, the refractive index of the material of the prism must be :

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A prism made up of flint glass is such that the incident ray does not emerge from the second surface. Critical angle for flint glass is . Then, refracting angle A must be

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White light is split into a spectrum by a prism and it is seen on a screen. If we put another identical inverted prism behind it in contact, what will be seen on the screen?

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A ray of light is incident on a hollow glass prism as shown. Then the ray will undergo :

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Light enters an isosceles right triangular prism at normal incidence through face AB and undergoes total internal reflection at face BC as shown below.
The minimum value of the refractive index of the prism is close to

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In which of the following the final image is erect ?

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Two lenses of focal lengths and are used to prepare an astronomical telescope. The minimum tube length will be : (final image is at )

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How should people wearing spectacles work with a microscope?

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In optical instruments, the lenses are used to form images by :

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If the focal length of a magnifying glass is 2.5 cm, it can magnify an object

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The magnifying power of an astronomical telescope is , then the ratio of the focal length of the objective to the focal length of the eyepiece is : (final image is at )

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The sum of the focal lengths of the objective and an eyepiece, in case of an astronomical telescope. is equal to : (final image is at )

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In case of an astronomical telescope, the distance between the objective lens and the eyepiece is equal to : (final image is at )

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In aerial mapping a camera uses a lens with a focal length. The height at which the airplane must fly, so that the photograph of a long strip on the ground fits exactly on the long filmstrip of the camera, is

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A simple camera with a converging lens of 60 mm focal length is focused on very far objects. To focus the camera on a nearby object 1.5 m away, the distance between the film and lens will have to be

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The figure shows a ray of light incident on a convex lens, parallel to its principal axis. Obviously the emergent ray passes through the principal focus F. Which of the following statements is correct ?

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Exercise

45 Qs

Related questions

In a plane perpendicular to the magnetic meridian the dip needle will remain :

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A magnet is placed in earth's magnetic field with north pole of the magnet pointing north. At the neutral point:

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The angle of dip at equator is :

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The S.I. unit of magnetic field intensity is :

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When a bar magnet is broken into two pieces :

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What will be the magnitude of e.m.f. induced in a 200 turns coil with cross section area 0.16? The magnetic field through the coil changes from 0.10 Wb to 0.30 Wb, at a uniform rate over a period of 0.05 s:

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A wire 88 cm long bent into a circular loop is placed perpendicular to the magnetic field of flux density 2.5 Wb. Within 0.5 s, the loop is changed into a square and flux density is increased to 3.0 Wb. The value of e.m.f. induced is :

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A magnetic field of flux density 10 T acts normal to a coil of 50 turns having 100 em-area. The e.m.f. induced if the coil is removed from magnetic field in 0.1 second is:

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A bar magnet has been cut equally lengthwise and widthwise to give four equal pieces. The pole strength of each piece as compared to the pole strength of the original bar magnet is :

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If strength of magnetic field and area vector is then find the magnetic flux link with area vector

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Consider points A,B,C,D on a horizontal cardboard equidistant from centre O as shown in the figure. A copper wire perpendicular to the cardboard passes through the centre O and carries an electric current flowing upwards. Deflection of magnetic needle will be maximum when it is  kept at the point.

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Which of the following statements is INCORRECT?

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Two charges of same magnitude move in two circlesof radii  and in a region of constant uniform magnetic field The work , and done by the magnetic field in the Two cases, respectively are such that:

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A wire carries a current I amperes shown in figure. The semicircle has a radius r. The magnetic filed at the centre C will be :

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A coil of one turn is made of a wire of certain length and then from the same length a coil of two turns is made. If the same current is passed in both the cases, then the ratio of the magnetic induction at their centres will be :

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A wire loop PQRS formed by joining two semi-circular wires of radii and carries a current I as shown in the following diagram. The magnetic induction at the centre O is :

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A wire loop formed by joining two semi-circular wires of radii and carries a current as shown in the adjoining diagram. The magnetic induction at the centre O is :

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A long copper wire is wound in the form of a coil of radius r. A current of 2 A is passed through this coil and the magnetic induction at the centre of this coil is noted. The same wire is now folded end to end and coil of the same radius r is prepared and the same current is passed through it. The magnetic induction at the centre:

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An electron moving to the east in a horizontal plane is~ deflected towards south by a magnetic field. The direction of this magnetic field is :

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When an electric current I is passed through a solenoid in the figure shown below, magnetic field at points A and B is equal and opposite to that of the earth. The,

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A wire carrying a current of 5 A is placed perpendicular to a magnetic induction of 2T. The force on each centimeter of the wire is :

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An electron has a circular path of radius 0.01 m in a perpendicular magnetic induction T. The speed of the electron is nearly:

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Two infinitely long wires P and Q separated by a distance of 10 cm in air, carry currents 1 and 21 in opposite directions as shown in the figure. The resultant magnetic field due to currents in these wires will be zero at :

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The phenomenon of electromagnetic induction is ;

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A magnet is dropped freely towards a loop of copper wire as shown in figure. The acceleration of magnet will be:

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Current is induced in a coil by electromagnetic induction when :

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By inserting an iron core in a coil carrying current, the strength of its magnetic field will :

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A transformer is a device which gives:

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A transformer steps up an AC supply from 220 V to 2200 V. If the secondary coil of the transformer has 2000 turns, the number of turns in its primary coil will be :

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A step down transformer reduces 220V to 11V. The primary coil draws 5 A current and secondary coil supplies 90A. Efficiency of the transformer will be:

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Voltage induced in the secondary coil of a transformer is mainly due to :

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The effect of using split rings in a simple DC motor is that:

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A step-up transformer of turns ratio 2 : 1 has 50 Hz AC voltage applied to primary. The frequency of AC output voltage across secondary is :

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Mutual induction is the principle of:

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In a transformer, the number of turns of primary coil and secondary coil are 5 and 4 respectively. If 220 V is applied on the primary coil, then the ratio of primary current to the secondary current is :

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An ideal transformer has 500 and 5000 turns in primary and secondary winding respectively. If the primary coil is connected to a 6 V battery then the secondary voltage is : 

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In a primary coil 5 A current is flowing on 220 volts. If the secondary coil produces 2200V voltage. Then the ratio of number of turns in secondary coil and primary coil will be :

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A transformer is used to light a 120 W, 24 V lamp from 240 V a.c. mains. The current in the main cable is 0.6 A. The efficiency of the transformer is :

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In a transformer the output current and voltage are 4 A and 20 V respectively. If the ratio of number of turns in the primary and secondary coil is 2 : 1 respectively, what is the input current and voltage?

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The device which is used for converting mechanical energy into electrical energy is called:

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The device which is used for converting electrical energy into mechanical energy is called:

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The effect of using split rings in a simple DC motor is that ;

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A direct current (DC) motor is connected to a battery by means of two leads. The motor moves for slightly lessthan half the cycle and comes to halt. Which of the following components is missing?

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A transistor based radio receiver set (effective resistance of the order of 18 ohms) operates on a 9V dc battery. If this replaced by a dc power supply with rating 9V, 500A then:

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The AC produced in India changes Its direction in every:

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Exercise

63 Qs

Related questions

Conductivity of superconductor is

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Two charges of +1 C & + 5 C are placed 4 cm apart, the ratio of the force exerted by both charges on each other will be :

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Which of the following relation is wrong?

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 Coulomb of charge contains .......... electrons

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5 charges each of magnitude and mass 1 kg are placed (fixed) symmetrically about a movable central charge of magnitude C and mass 0.5 kg as shown. The charge at is removed. The acceleration of the central charge is :
[Given in SI units]

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positive charges each of magnitude q are placed on a circle of radius in a manner such that they are equally spaced. A charge is placed at the centre. If one of the charges q is removed, then the force on is :

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In a neon discharge tube  Ne" ions move to the right per second while electrons move to the left per second. Therefore, the current in the discharge tube is

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If Q = 2 coloumb and force on it is F = 100 newton, then the value of field intensity will be

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In the electric field of charge Q, another charge is carried from A to B. A to C, A to D and A to E, then work done will be

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A negatively charged particle initially at rest is placed in an electric field that varies from point to point. There are no other fields. Then :

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Two charges and are placed at a distance apart as shown in the figure. 
The electric field at a point on the perpendicular bisector is shown as :

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Two charges +Q and -2Q are located at points A and B on a horizontal line as shown
The electric field is zero at a point which is located at a finite distance

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There are three resistance 5, 6 and 8  connected in parallel to a battery of 15 V and of negligible resistance. The potential drop across 6 resistance is

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In the given circuit, the equivalent resistance between points A and B will be

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Resistance of a conductor of length 75 cm is 3.25. What will be the length of a similar conductor whose resistance is 13.25 ?

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A piece of wire of resistancec 4 is bent through  at its mid point and the two halves are twisted together then resistance is

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In how many parts (equal) a wire of 100 be cut so that a resistance of 1 is obtained by connecting them in parallel ?

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Two copper wires, one of length 1 m and the other of length 9 m, are found to have the same resistance. Their diameters are in the ratio

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Reading of ammeter in ampere for the following circuit is

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Two resistors are joined in series, then their equivalent resistance is 90 0. When the same resistors are joined in parallel, the equivalent resistance is 20  The resistances of the two resistors will be

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In the ladder network shown, current through the resistor 3 is 0.25 A. The input voltage 'V' is equal to

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The reading of voltmeter is

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What is the ammeter reading?

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Three identical bulbs are connected in parallel with a battery. The current drawn from the battery is 6 A. If one of the bulbs gets fused, what will be the total current drawn from the battery ?

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A uniform wire of resistance R is uniformly compressed along its length, until its radius becomes n times the original radius. Now, the resistance of the wire becomes

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The resistance of a wire of cross-section 'a' and length 'l' is R ohm. The resistance of another wire of the same material and of the same length but cross-section '4a' will be

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In the following circuit the value of total resistance between X and Y in ohm is

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Wires A and B are made from the same material. Wire A has length 12m and weight 50 g, while wire B is 18 m long and weighs 40 g. Then the ratio of their resistances will be

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In case of the circuit arrangement shown below, the equivalent resistance between A and B is

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The net resistance between points P and Q in the circuit shown in fig. is

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A wire of resistance 10.0 ohm is stretched so as to increase its length by 20%. Its resistance then would be

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In the circuit shown below, all the resistances are equal, each equal to R. The equivalent resistance between points A and C is

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A battery of 10 V and negligible internal resistance is connected across the diagonally opposite corner of a cubical network consisting of 12 resistors each of resistance 1. The total current I in the circuit external to the network is

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Figure (a) below shows a Wheatstone bridge in which P, Q, R, S are fixed resistances, G is a galvanometer and B is a battery. For this particular case the galvanometer shows zero deflection. Now, only the i positions of B and G are interchanged,. as shown in the figure (b). The new deflection of the galvanometer

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In the circuit arrangement shown, if the pointAand 8 are joined by a wire the current in this wire will be

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In the following circuit, each resistor has a resistance of 15  and the battery has an e.m.f. of with negligible internal resistance
When a resistor of resistance R is connected between & F, no current flows through the galvanometer (not shown in the figure) connected between C & F. Calculate the value of R

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The circuit given below is for the operation of an industrial fan. The resistance of the fan is . The regulator provided with the fan is a fixed resistor and a variable resistor in parallel. Under what value of the variable resistance given, power transferred to the fans will be maximum? The power source of the fan is a dc source with internal resistance of

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When all the resistances in the circuit are 1 each, then the equivalent resistance across points A & B will be

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A cylindrical copper rod has length L and resistance R. If it is melted and formed into another rod of length 2L. the resistance will be

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There are four resistors of 12 ohm each. Which of the following values is/are possible by their combinations (series and / or parallel)

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In case of the circuit shown below, which of the following statements is/are true?

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A current i reaching at a point in a circuit gets branched and flows through two resistors and . Then, the current through  varies as

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In the circuit shown below

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We are given n resistors, each of resistance R. The ratio of the maximum to minimum resistance that can be obtained by combining them is

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A cell of emf E is connected across a resistance R. The potential difference between the terminals of the cell is found to be V. The internal resistance of the cellis given as

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In which of the following cells, the potential difference between the terminals of a cell exceeds its emf

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A cell, an ammeter and a voltmeter are all connected in series. The ammeter reads a current I and the voltmeter a potential difference V. If a torch bulb is connected across the voltmeter, then.

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In the process of electrostatic induction

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Consider the circuit below. The bulb will light up if

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An electric iron of heating element of resistance 88  is used at 220 volt for 2 hours. The electric energy spent, in unit, will be

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Two identical heater wires are first connected in series and then in parallel with a source of electricity. The ratio of heat produced in the two cases is

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You are given three bulbs 25 W, 40 W and 60 W . Which of them has the lowest resistance?

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If and are the filament resistances of a 200 W bulb and a 100 W bulb respectively designed to operate on the same voltage, then

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When a voltage of 20 volt is applied between the two ends of a coil, 800 cals heat is produced in 1 second. The value of resistance of the coil is (1 calorie = 4.2 joule)

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You are given two fuse wires A and B with current rating 2.5 A and 6 A respectively. Which of the two wires would you select for use with a 1100 W, 220 V room heater?

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An electric current of 2.0 A passes through a wire of resistance 25 . How much heat (in joule) will be developed in 1 minute?

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Two bulbs, one of 200 W and the other of 100 W, are connected in series with a 100 V battery which has no internal resistance. Then,

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An electric heater consists of a nichrome coil and runs under 220 V, consuming 1 kW power. Part of its coil burned out and it was reconnected after cutting off the burnt portion, The power it will consume now is

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In the following circuit, the 10 resistor dissipates power P. If the resistor is replaced by 90, the power dissipated in it is

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A neon lamp is connected to a voltage a.c. source. The voltage is gradually increased from zero volt. It is observed that the neon flashes at 50 V. The a.c. source is now replaced by a variable dc source and the experiment is repeated. The neon bulb will flash at

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A certain network consists of two ideal and indentical voltage sources in series and a large number of ideal resistor. The power consumed in one of the resistor is 4 W when either of the two sources is active and other is replaced by a short circuit. The power consumed by same resistor when both sources are simultaneously active would be

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The circuit shown has 3 identical light bulbs A, B, C and 2 identical batteries . When the switch is open, A and B glow with equal brightness, When the switch is closed

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A student connects two lamps in the circuit shown.The emf of the two batteries is different
Which of the following statements are correct ?
i. When keys 1, 2, 3 and 4 are closed, bulbs A and B will both glow
ii. When key 2 and 4 are closed bulb A will glow
iii.When 1 and 4 are closed, bulb A will glow
iv.When 2, 3 and 4 are closed, both A and B will glow

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