Question

In the potentiometer arrangement shown, the driving cell D has emf E and internal resistance r. The cell C, whose emf is to be measured, has emf E/2 and internal resistance 2r. The potentiometer wire is 100 cm long. If balance is obtained, the length $AJ=l$

• A. $l=50cm$
• B. l > 50 cm
• C. balance will be obtained only if resistance of AB is > r
• D. balance cannot be obtained

Answer 1

Answer: (B), (C)

The correct options are
B l > 50 cm
C balance will be obtained only if resistance of AB is > r

$V_A-V_B<E$

$V_A-V_P=\frac{E}{2}$

$\frac{V_A-V_B}{V_A-V_p}=\frac{l_o}{l}$

$V_A-V_B=<E$

or

$l>50cm$