Question

A 600 cg potentiometer wire is connected to a circuit as shown in figure. The resistance of potentiometer wire is 15r. The distance from point A at which the jockey should touch the wire to get zero deflection in the galvanometer is–

• A. 320 cm
• B. 230 cm
• C. 160 cm
• D. 460 cm

Answer 1

Answer: (A)

320 cm

Answer 2

Current flowing through potential wire is –

I = $\frac { E } { 15 r + r }$ =

Potential drop across potential wire is,

V = I × 15 r = $\frac { 15 \mathrm { E } } { 16 }$

Potential gradient, K =

\ $\frac { E } { 2 }$ = Kl or $\frac { E } { 2 }$ = × l

or l = $\frac { 16 \times 600 } { 15 \times 2 }$ = 320 cm.