Question

In the figure battery E is balanced on 55 cm length of potentiometer wire but when a resistance of 10W is connected in parallel with the battery then it balances on 50 cm length of the potentiometer wire. The internal resistance r of the battery is-

• A. 1 W
• B. 3 W
• C. 10 W
• D. 5 W

Answer 1

Answer: (A)

1 W

Answer 2

r = $\left( \frac { \ell _ { 1 } - \ell _ { 2 } } { \ell _ { 2 } } \right) ( \mathrm { RB } )$