Question

In the potentiometer experiment, the balancing length with cell E₁ of unknown e.m.f. is ℓ₁ cm. By shunting the cell E₁ with resistance 'R' which is equal to internal resistance (r) of the cell E₁, the balancing length ℓ₂ is ______

Options

• `ℓ_1/2`

• `ℓ_1/4`

• `ℓ_1`

• `2ℓ_1`

Answer 1

In the potentiometer experiment, the balancing length with cell E₁ of unknown e.m.f. is ℓ₁ cm. By shunting the cell E₁ with resistance 'R' which is equal to the internal resistance (r) of the cell E₁, the balancing length ℓ₂ is `underline(ℓ_1/2)`.

Explanation:

`R = R^'((ℓ_1 - ℓ_2)/2)`

`ℓ_2 = ℓ_1 - ℓ_2`

`2ℓ_2 = ℓ_1`

∴ `ℓ_2 = ℓ_1"/"2`