Question 1

Two layers of cloth of equal thickness provide warmer covering than a single layer of cloth of double the thickness, because they :

Accepted Answer

Air is a bad conductor of heat, hence if layer of air is isolated between two layers of cloth, warmer covering will be provided than if only one layer of cloth, where only body is isolated from surrounding air by cloth.

Question 2

When a body has the same temperature as that of its surroundings :

Accepted Answer

Since the body has the same temperature as that of surrounding, it is in thermal equilibrium with the surroundings.So, there is no net exchange of heat.So, amount of heat radiated = amount of heat received from the surroundings.

Question 3

Which of the following methods of flow of heat is (are) based on gravitational attraction?

Accepted Answer

Convectional currents that are set up in vessels having considerable height, work on the principle that cooler, denser water tries to move downwards on account of its larger weight while the water closer to the heater i.e. the water at lower height gets heated up and tries to move upwards on account of lower weight.

Question 4

In a room containing air, heat can go from one place to another by :

Accepted Answer

Heat can travel by conduction as material medium is available as wall.Heat can travel by convection as material medium is available as air.Heat can travel by radiation as no material medium is needed.

Question 5

Assertion (A): Woolen clothes keep the body warm in winterReason (R): Air is bad conductor of heat

Accepted Answer

Woollen clothes effectively separate the body from surrounding air by entrapping a layer of air.Since both wool and air are bad conductors of heat on varying levels, it creates separation that keeps bodies warm.

Question 6

A) Heat transfer by conduction and convection require a material medium.B) Heat transfer by radiation doesn't require a material medium.

Accepted Answer

Conduction and convection are processes where heat is transferred by the collision of molecules. Hence, for these processes to take place, we need a material medium.In radiation, heat travels as electromagnetic waves which do not require a medium to travel. Its transfer mechanism is completely independent of the medium.

Question 7

In the following, which statement is correct :
a) A hot body emits hot radiations only.
b) A cold body absorbs the radiations only.
c) A cold body emits cold radiations only.
d) All the bodies emit and absorb radiations simultaneously.

Accepted Answer

Since, we know that, Above zero kelvin, all the bodies emit and absorb radiations simultaneously.Therefore, "All the bodies emit and absorb radiations simultaneously" is the correct statement.

Question 8

Celsius is a unit of :

Accepted Answer

A thermometer is a device that we use to measure temperature of the given body. A rise in temperature of the body causes a change in property of the substance and we use this to measure temperature. The unit of measuring temperature is celsius,The Centigrade (Celsius) Scale: This scale has lower fixed point as the melting point of ice and upper fixed point as boiling point of water and between the two points is divided into 100 equal parts.

Question 9

The range of clinical thermometer is:

Accepted Answer

The clinical thermometer is a specially designed thermometer to measure body temperature. The range of a clinical thermometer is centered around the human body temperature which is from  35^\circ C  to  42^\circ C .

Question 10

Radiation is passing through a transparent medium, then :

Accepted Answer

Opacity affects radiation; Transparency which is essentially lacks opacity actually allows radiation through it. Hence, the temperature doesn't alter.

Heat

Physics
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Two layers of cloth of equal thickness provide warmer covering than a single layer of cloth of double the thickness, because they :

When a body has the same temperature as that of its surroundings :

Which of the following methods of flow of heat is (are) based on gravitational attraction?

In a room containing air, heat can go from one place to another by :

Assertion (A): Woolen clothes keep the body warm in winter
Reason (R): Air is bad conductor of heat

A) Heat transfer by conduction and convection require a material medium.
B) Heat transfer by radiation doesn't require a material medium.

In the following, which statement is correct :
a) A hot body emits hot radiations only.
b) A cold body absorbs the radiations only.
c) A cold body emits cold radiations only.
d) All the bodies emit and absorb radiations simultaneously.

Celsius is a unit of :

The range of clinical thermometer is:

Radiation is passing through a transparent medium, then :

Heat

Physics 10031 Views

Two layers of cloth of equal thickness provide warmer covering than a single layer of cloth of double the thickness, because they :

When a body has the same temperature as that of its surroundings :

Which of the following methods of flow of heat is (are) based on gravitational attraction?

In a room containing air, heat can go from one place to another by :

Assertion (A): Woolen clothes keep the body warm in winter Reason (R): Air is bad conductor of heat

A) Heat transfer by conduction and convection require a material medium.B) Heat transfer by radiation doesn't require a material medium.

In the following, which statement is correct : a) A hot body emits hot radiations only. b) A cold body absorbs the radiations only. c) A cold body emits cold radiations only. d) All the bodies emit and absorb radiations simultaneously.

Celsius is a unit of :

The range of clinical thermometer is:

Radiation is passing through a transparent medium, then :

Physics
10031 Views

Assertion (A): Woolen clothes keep the body warm in winter
Reason (R): Air is bad conductor of heat

A) Heat transfer by conduction and convection require a material medium.
B) Heat transfer by radiation doesn't require a material medium.

In the following, which statement is correct :
a) A hot body emits hot radiations only.
b) A cold body absorbs the radiations only.
c) A cold body emits cold radiations only.
d) All the bodies emit and absorb radiations simultaneously.