Question

In the meter bridge experiment, a null point was obtained at a distance of ℓ from the left end. The values of resistances in the left and right gaps are doubled and then interchanged. The new position of a null point is ______

Options

• `(100 - ℓ/2)`

• (100 - 2ℓ)

• (100 - ℓ)

• `(100 - ℓ/4)`

Answer 1

In the meter bridge experiment, a null point was obtained at a distance of ℓ from the left end. The values of resistances in the left and right gaps are doubled and then interchanged. The new position of a null point is (100 - ℓ).

Explanation:

When the resistances are interchanged the lengths get interchanged. Hence the new position of the null point will be at (100 - ℓ) from the left end. Doubling of the resistances does not affect the null point because the ratio of the resistance remains the same.