Question

How will the sensitivity of the metre bridge change under following condition rheostat head is moved from minimum resistance to the maximum resistance positions

Answer 1

When rheostat head is moved from minimum resistance to the maximum resistance position then sensitivity of the meter bridge will decrease.

• Sensitivity of the meter bridge means it can compare very small electromotive force (emf) of the cell.
• This is possible if we move the jokey by very small distance then it will provide sufficient deflection so we can get exact null point.
• Now if we move rheostat head from minimum resistance to maximum resistance the net resistance of circuit will increase which leads to the decrease in current.
• This further leads to the decrease in potential difference across the meter bridge.
• Hence very small potential difference can be measured by large distance.
• Large displacement of slider gives a very small potential difference so sensitivity will decrease.