Question

Two equal resistances are connected in the gaps of a meter bridge. If the resistance in the left gap is increased by $10\%$, the balancing point shift :

• A. $10\%$ to right
• B. $10\%$ to left
• C. $9.6\%$ to right
• D. $4.8\%$ to right

Answer 1

The correct option is D $4.8\%$ to right

Let the Resistance be R,

Initially

$\frac{R}{R}=\frac{l}{100-l}$

$\Rightarrow l=50cm$

After 10% increase it is,

$\Rightarrow \frac{1.1R}{R}=\frac{l}{100-l}$

$\Rightarrow 110=2.1l$

$\Rightarrow l=\frac{110}{2.1}=52.38$

$\Rightarrow \frac{\Delta l}{l}\times 100=\frac{2.38}{50}\times 100\approx 4.8$%