A resistance R is to be measured using a meter bridge. Student chooses the standard resistance S to be 100. He finds the null point at l1 = 2.9 cm. He is told to attempt to improve the accuracy. Which of the following is a useful way?

Question

A resistance R is to be measured using a meter bridge. Student chooses the standard resistance S to be 100. He finds the null point at l1 = 2.9 cm. He is told to attempt to improve the accuracy. Which of the following is a useful way?

Philoid · Accepted Answer

A meter bridge works on the principle of a Wheatstone bridge. In a meter bridge, we need to adjust the resistances and have a balance point in the middle of the bridge.

For a balanced meter bridge, we have the following equation

Therefore, for balance point to lie in the middle, l₁ = 50cm, this means R=S.

To find R, we again use the above equation, where S=100, l₁ = 2.9cm.

Therefore, he should change the resistance to 3Ω.