In a potentiometer, the null point is obtained on 7th wire. What should we do to change the null point on 9th wire by keeping all other quantities same? (a) Decrease resistance in series with battery (b) Increase resistance in main Circuit (c) Decrease resistance in main circuit (d) Increase applied e.m.f.

Answer: (b). Balancing length l = E/k; to move the null point further (7th to 9th wire) k must decrease. k = I × (resistance per length), so the current in the main circuit must decrease. Increasing the series (rheostat) resistance in the main circuit lowers the current. So the answer is (b) increase resistance in main circuit.

In a potentiometer, the null point is obtained on 7th wire. What… | MHT CET 2026 (13 May, Shift 1)

Q9MHT CET 2026 · 13 MAY · SHIFT 1Easy

Potentiometer

In a potentiometer, the null point is obtained on $7^{th}$ wire. What should we do to change the null point on $9^{th}$ wire by keeping all other quantities same?

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Answer: (b)

Balancing length $l = \frac{E}{k}$ ; to move the null point further (7th to 9th wire) $k$ must decrease.
$k = I \times (\text{resistance per length})$ , so the current in the main circuit must decrease.
Increasing the series (rheostat) resistance in the main circuit lowers the current.
So the answer is (b) increase resistance in main circuit.

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Potentiometer question from MHT CET 2026 (13 May, Shift 1)

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