Question

In a practical meter bridge setup, resistance and null point are as shown


Assuming end correction at $\text{A}$ and $\text{B}$ are equal, calculate end correction at $\text{A}$.

• A. $25\text{cm}$
• B. $1.5\text{cm}$
• C. $1\text{cm}$
• D. $0.5\text{cm}$

Answer 1

The correct option is C $1\text{cm}$

Let $x$ be the end correction at $\text{A}$ and $\text{B}$

Since, a null point is achieved by balancing potential drops in a circuit. The potential difference between the points is zero, i.e. points are at the same potential.

So, using the concept of null point, we write,

$\frac{R}{X}=\frac{l_1+x}{l_2+x}$

$\Rightarrow \frac{R}{X}=\frac{35+x}{65+x}$$=\frac{6}{11}$

$6(65+x)=11(35+x)$

$390+6x=385+11x$

$\begin{array}{c}x=1\text{cm}\end{array}$