Question

The resistances in left and right gap of a meter-bridge are 3 `Omega` and 5 `Omega` respectively. When the resistance in the left gap is increased by 10%, the balance point shifts nearly by ______.

Options

• 4.4 cm to the left

• 2.2 cm to the right 

• 2.2 cm to the left

• 4.4 cm to the right

Answer 1

The resistances in left and right gap of a meter-bridge are 3 `Omega` and 5 `Omega` respectively. When the resistance in the left gap is increased by 10%, the balance point shifts nearly by 2.2 cm to the right.

Explanation:

`l/(100-l) = 3/5`

`5l = 300 - 3l`

`8l = 300`

`l = 300/8`

`(l^')/(100-l^') = 3.3/5`

`5l^' = 330 - 3.3l^'`

`8.3l^' = 330`

`l^' = 330/8.3`

`l = l^' = 300/8 - 330/8.3 approx 2.2  "cm to the right"`