Potentiometer is an ideal instrument .Because
(A)No current is drawn from the souce of unknown e.m.f
B) Current is drawn from the source of unknown e.m.f
C) It gives deflection even at null point
D) It has variable potential gradient

A battery of e.m.f. 10 V and internal resistance 2 Omega is connected in primary circuit with a uniform potentiometer wire and a rheostat whose resistance is fixed at 998 Omega .A battery of unknown e.m.f. is being balanced on this potentiometer wire and balancing length is found to be 50 cm.When area of cross section of potentiometer wire is doubled, then balancing length is found to be 75 cm. (i)Calculate e.m.f. of the battery. (ii)Calculate resistivity of potentiometer wire if length of wire is 100 cm and area of cross-section (initially) is 100 cm^2 .

A potentiometer wire of Length L and a resistance r are connected in series with a battery of e.m.f. E_(0) and a resistance r_(1) . An unknown e.m.f. E is balanced at a length l of the potentiometer wire. The e.m.f. E will be given by :

In the circuit shown the ideal ammeter A reads a current of I_1 , A . Now the source of e.m.f . and the ammeter are physically interchanged , i.e. . the source is out between B and C and the ammeter between A and B . The ammeter now reads a current of I_2 A . Then -

In the circuit shown, a meter bridge is in its balanced state. The meter bridge wire has a resistance .1 ohm//cm . The value of unknown resistance X and the current drawn from the battery of negligible resistance is

In the circuit shown, a meter bridge is in its balanced state. The meter bridge wire has a resistance .1 ohm//cm . The value of unknown resistance X and the current drawn from the battery of negligible resistance is

AB is a potentiometer wire of length 100cm and its resistance is 10ohm. It is connected in series with a resistance R=40 ohm and a battery of e.m.f. wV and negigible internal resistance. If a source of unknown e.m.f. E is balanced by 40cm length of the potentiometer wire, the value of E is:

The e.m.f. of a cell is 6 volt. When 2 ampere current is drawn from it then th e potential difference across its terminal remains 3 volt. Its internal resistance.

For a cell, the graph between the potential difference (V) across the terminals of the cells and the current I drawn from the cell is as shown in figure. Calculate the e.m.f. and the internal resistance of the cell.

Figure shows a potentiometer arrangemeter with R_(AB)=10 Omega and rheostat of variable resistance d. For x=0 null deflection point is found at 20 cm from A . For unknown value of x null deflection point was at 30 cm from A , then the value of x is

A 10 m along uniform metallic wire having a resistance of 20Omega is used as a potentiometer wire. This wire is connected in series with another resistance of 480 Omega and a battery of emf 5 V having negligible internal resistance . If an unknown emf e is balanced across 6 m of the potentiometer wire. Calculate : (i) The potential gradient across the potentiometer wire. (ii) the value of the unknown emf e.