Question

In a meter bridge, the gaps are closed by resistances $2$ and $3$ ohms. The value of shunt to be added to $3$ ohm resistor to shift the balancing point by $22.5cm$ is.

• A. $1\Omega$
• B. $2\Omega$
• C. $2.5\Omega$
• D. $5\Omega$

Answer 1

Answer: (B)

$2\Omega$

Case 1 - No shunt

$\Rightarrow \frac{2}{3}=\frac{l}{100-l}$

$200=5l$

$l=40cm$

Case 2 - When shunt is added.

$\Rightarrow \frac{2(3+X)}{3X}=\frac{62.5}{37.5}$

$6+2X=5X$

$\Rightarrow 3X=2\times 3$

$X=2\Omega$