Question

In a meter bridge setup, given that $R=10\Omega ,X=15\Omega$ and end error at $\text{A, B}$ is $1\text{cm},3\text{cm}$ respectively.

Find error in measurement of null point, before considering end correction at $\text{A}$ and $\text{B}$.

• A. $0.2\text{cm}$
• B. $0.6\text{cm}$
• C. $0.5\text{cm}$
• D. $0.8\text{cm}$

Answer 1

The correct option is B $0.6\text{cm}$

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.

When end correction is not considered,

$\frac{10}{l_1}=\frac{15}{100-l_1}$

$1000=25l_1$

$l_1=40\text{cm}$

When end correction is considered,

$\frac{10}{l_1+1}=\frac{15}{-l_1+3+100}$

$206-2l_1=3l_1+3$

$203=5l_1$

$l_1=40.6\text{cm}$

Error $=40.6-40=0.6\text{cm}$