A resistance R is to be measured using a meter bridge. Student chooses the standared resistance S to be `100 Omega`. He finds the null point at `l_(1)=2.9cm`. He is told to attempt to improve the accuracy. Which of the folllowing is a useful way?

Options

A. He should measure `l_(1)` more accurately
B. He should change S to `1000 Omega` and repeat the experiment
C. He should change S to `3 Omega` and repaeat the experiment
D. He should give up hope of a more accurate measurement with a meter bridge

Answer

C

Explanation

As meter-bridge is balanced, so `(2.9)/(100-2.9)=(R)/(S)=(R)/(100)` or `R=(100xx2.9)/(97.1)=3 Omega`
The meter-bridge is of the same order. Therefore a student must use `5=3 Omega` improve the accuracy of the measurement of resistance R hence, option (c) is correct.