Question

In a meter bridge circuit as shown in the figure, the bridge is balanced when $AJ=20 \, cm$ . On interchanging $P$ and $Q$ the balance length shifts by

• A. zero
• B. $80 \, cm$
• C. $40 \, cm$
• D. $60 \, cm$

Answer 1

Answer: (D)

Initially balancing point is $J$ ,
Hence $\frac{AJ}{BJ}=\frac{P}{Q}=\frac{20}{80}$
Now if $P$ & $Q$ are interchanged,
Let balancing point be $J_{1}$
$\frac{AJ_{1}}{BJ_{1}}=\frac{Q}{P}=\frac{80}{20}$
The balanced point shifts by $AJ_{1}-AJ=80-20=60 \, cm$ .