Question

The figure shows a metre-bridge circuit, with AB = 100 cm, X = 12 W and R = 18 W, and the jockey J in the position of balance.

If R is now made 8 W, through what distance will J have to be moved to obtain balance?

• A. 10 cm
• B. 20 cm
• C. 30 cm
• D. 40 cm

Answer 1

Answer: (B)

20 cm

Answer 2

= for balance

Initially, $\frac { 12 } { 18 }$ =, finally $\frac { 12 } { 8 }$= $\frac { l ^ { \prime } } { 100 - l ^ { \prime } }$

or JJ′ = l′ – l = 20 cm