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Two cells of emfs approximately 5V and 1...

Two cells of emfs approximately 5V and 10V are to be accurately compared using a poteniometer of length 400 cm.

A

The battery that runs the potentiometer should have voltage of 8 V.

B

The battery of potentiometer can have a voltage of 15 V and R adjusted so that the potential drop across the wire slightly exceeds 10 V.

C

The first portion of 50 cm of wire itself should have a potential drop of 10 V

D

Potentiometer is usually used for comparing resistances and not voltages.

Text Solution

Verified by Experts

The correct Answer is:
B
As `R=rho(l)/(A)` resistance is maximum when l is large and A is least. For the give dimensions of wire, resistane will be maximum for l=10cm and `A=1cmxx(1)/(2)cm`
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