Q: In comparing e.m.f.s of 2 cells with the help of potentiometer, at the balance point, the current flowing through the wire is taken from:

emf of secondary cell \$ = I \ r \ l\$whereI - current in the main circuit from battery.r - resistance per unit length of wire.l - balancing length.

Q: Choose the correct statement:

When the battery is discharging, the terminals voltage of the battery is always \$\le\$ Emf of cell \$[\because r > 0]\$ \$\therefore \$ There will always be a difference which is defined to be lost volt.

Question 1

Kirchoffs law of junctions is also called the law of conservation of:

Accepted Answer

Kirchoff's second law:- According to the law, at a particular junction the charge entering the junction is equal to charge exiting that junction.$ \Rightarrow$ There is no charge accumulated at junction. This is also called as law of conservation of charge.

Question 2

Kirchhoff's law of meshes is in accordance with law of conservation of:

Accepted Answer

Kirchhoff's law:  In a loop the summation of P.D across every element is zero which can also be interpreted as the energy delivered by battery is dissipated only through the dissipating elements. This corresponds to the law of conservation of energy.

Question 3

In comparing e.m.f.s of 2 cells with the help of potentiometer, at the balance point, the current flowing through the wire is taken from:

Accepted Answer

emf of secondary cell $ = I \ r \  l$whereI - current in the main circuit from battery.r - resistance per unit length of wire.l - balancing length.

Question 4

A steady current is passing through a linear conductor of non uniform cross-section.  The net quantity of charge crossing any cross section per second is

Accepted Answer

The quantity of charge passing through any cross-section per second is nothing but current flowing in the conductor.As given, the current is steady current, means current is uniform throughout the cross-section. Hence it is independent of Area of cross section.

Question 5

Assertion(A) : The e.m.f of the cell in secondary circuit must be less than e.m.f of cell in primary circuit in potentiometer.
Reason (R): Balancing length cannot be more than length of potentiometer wire.

Accepted Answer

When the e.m.f of secondary cell is greater than the primary cell, it implies that the balancing length is greater than the available length. Therefore we cant measure the e.m.f of secondary cell.$\therefore$  E. M.F of of secondary cell < E.M.F of primary cell.Hence assertion and reason both are correct and reason is the correct explanation of the assertion.

Question 6

Choose the correct statement:

Accepted Answer

When the battery is discharging, the terminals voltage of the battery is always $\le$ Emf of cell $[\because r > 0]$ $\therefore $ There will always be a difference which is defined to be lost volt.

Question 7

The sensitivity of a potentiometer can be increased by
a) increasing the series resistance in the primary circuit
b) decreasing the length of the potentiometer wire
c) using a thin and high resistivity wire as a potentiometer wire
d) increasing the length of the wire

Accepted Answer

The sensitivity of potentiometer is inversely proportional to the potential gradient.With increase in the series resistance the potential gradient of the wire decreases thereby helps us to measure the emf more accurately.Increase in the length of the wire decrease the potential gradient of the wire thereby helps us to measure the emf more accurately.

Question 8

Wheatstones&#8217;s bridge cannot be used for measurement of very _______ resistances.

Accepted Answer

From wheatstone bridge while measuring For resistances of very low value like few ohms , the effect of other components of the circuit like wires , galvanometer etc. might come into account. these components might introduce stray resistance to the calculation.Therefore we cannot apply wheatstone bridge for low resistance.

Question 9

For making standard resistance, wire of following material is used

Accepted Answer

Manganin is used to make standard resistors because 1) They have high value of resistivity.2) Temperature coefficient of resistance is less.3) They are least affected by temperature.

Question 10

With the increase in temperature, the ratio of conductivity to resistivity of a metal conductor:

Accepted Answer

With the increase of temperature, conductivity of a metal conductor decreases and resistivity increases. Therefore  the ratio of conductivity to resistivity decreases.

Current Electricity

Physics
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Kirchoffs law of junctions is also called the law of conservation of:

Kirchhoff's law of meshes is in accordance with law of conservation of:

In comparing e.m.f.s of 2 cells with the help of potentiometer, at the balance point, the current flowing through the wire is taken from:

A steady current is passing through a linear conductor of non uniform cross-section. The net quantity of charge crossing any cross section per second is

Assertion(A) : The e.m.f of the cell in secondary circuit must be less than e.m.f of cell in primary circuit in potentiometer.
Reason (R): Balancing length cannot be more than length of potentiometer wire.

Choose the correct statement:

The sensitivity of a potentiometer can be increased by
a) increasing the series resistance in the primary circuit
b) decreasing the length of the potentiometer wire
c) using a thin and high resistivity wire as a potentiometer wire
d) increasing the length of the wire

Wheatstones’s bridge cannot be used for measurement of very _______ resistances.

For making standard resistance, wire of following material is used

With the increase in temperature, the ratio of conductivity to resistivity of a metal conductor:

Current Electricity

Physics 18436 Views

Kirchoffs law of junctions is also called the law of conservation of:

Kirchhoff's law of meshes is in accordance with law of conservation of:

In comparing e.m.f.s of 2 cells with the help of potentiometer, at the balance point, the current flowing through the wire is taken from:

A steady current is passing through a linear conductor of non uniform cross-section. The net quantity of charge crossing any cross section per second is

Assertion(A) : The e.m.f of the cell in secondary circuit must be less than e.m.f of cell in primary circuit in potentiometer. Reason (R): Balancing length cannot be more than length of potentiometer wire.

Choose the correct statement:

The sensitivity of a potentiometer can be increased by a) increasing the series resistance in the primary circuit b) decreasing the length of the potentiometer wire c) using a thin and high resistivity wire as a potentiometer wire d) increasing the length of the wire

Wheatstones’s bridge cannot be used for measurement of very _______ resistances.

For making standard resistance, wire of following material is used

With the increase in temperature, the ratio of conductivity to resistivity of a metal conductor:

Physics
18436 Views

Assertion(A) : The e.m.f of the cell in secondary circuit must be less than e.m.f of cell in primary circuit in potentiometer.
Reason (R): Balancing length cannot be more than length of potentiometer wire.

The sensitivity of a potentiometer can be increased by
a) increasing the series resistance in the primary circuit
b) decreasing the length of the potentiometer wire
c) using a thin and high resistivity wire as a potentiometer wire
d) increasing the length of the wire