Q. In the potentiometer experiment shown in figure-, the null point length is . Choose the correct options given below

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A

If jokey is shifted towards right, will increase

B

if value of is increased, is decreased

C

If value of is increased, is increased

D

If switch is closed, will decrease

Solution:

If switch is open,

where is the current in primary circuit and is resistance per unit length of potentiometer wire.
Thus at null point balancing length is given as

If jockey is shifted towards right, resistance in primary circuit will increase so current will decrease and will increase.
If is increased, will also increase so will decrease.
As with will increase.
If switch is closed then null point will be obtained corresponding to the potential difference

Which is less than so null point balancing length will decrease.

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