JEE Main · 2022 · 25 Jul 2022 · Shift 2 · Current Electricity

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In a potentiometer arrangement, a cell of emf 1.20 V gives a balance point at 36 cm length of wire. This cell is now replaced by another cell of emf 1.80 V. The difference in balancing length of potentiometer wire in above conditions will be ______ cm.

Answer: 18

Solution

In a potentiometer, the emf is proportional to the balancing length:

emf = (Potential Gradient) \times length

.

For the first cell:

1.2 = k \times 36

where

k

is the potential gradient.

For the second cell:

1.8 = k \times x

where

x

is the new balancing length.

Dividing these equations:

\frac{1.8}{1.2} = \frac{x}{36}

\frac{3}{2} = \frac{x}{36}

x = 54 cm

The difference in balancing lengths =

54 - 36 = 18

cm.

JEE Main · 2022 · 25 Jul 2022 · Shift 2 · Integer answer

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