Question

In a metre bridge, the balancing length from the left end (standard resistance of one ohm is in the right gap) is found to be $20cm$. The value of the unknown resistance is

• A. $4\Omega$
• B. $0.5\Omega$
• C. $0.4\Omega$
• D. $0.25\Omega$

Answer 1

The correct option is D $0.25\Omega$

For meter bridge:

$\frac{P}{Q}=\frac{l}{100-l}$ where $P=$ unknown resistance , $Q=$ known resistance, $l=$ balancing length.

Thus, $P=\frac{l}{100-l}\times Q=\frac{20}{100-20}\times 1=\frac{1}{4}=0.25\Omega$