In a meter bridge experiment to determine the value of unknown resistance, first the resistances $2 \Omega$ and $3 \Omega$ are connected in the left and right gaps of the bridge and the null point is obtained at a distance $l \mathrm{~cm}$ from the left. Now when an unknown resistance $\mathrm{x} \Omega$ is connected in parallel to $3 \Omega$ resistance, the null point is shifted by 10 cm to the right of wire. The value of unknown resistance $x$ is ____ $\Omega$.

JEE Main · 2026 · 24 Jan 2026 · Shift 2 · Current Electricity

In a meter bridge experiment to determine the value of unknown resistance, first the resistances

2Ω

and

3Ω

are connected in the left and right gaps of the bridge and the null point is obtained at a distance

l cm

from the left. Now when an unknown resistance

x Ω

is connected in parallel to

3Ω

resistance, the null point is shifted by 10 cm to the right of wire. The value of unknown resistance

x

is ____

Ω

Answer: 6

With

2 Ω

and

3 Ω

in the gaps, the balance condition

\frac{2}{3} = \frac{l}{100 - l}

gives

l = 40

cm. Shifting the null point

10

cm to the right makes it

50

cm, where

\frac{2}{R} = \frac{50}{100 - 50} = 1

, so the effective right-gap resistance is

R = 2 Ω

. This

R

3 Ω

in parallel with

x

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

, giving

3 x = 6 + 2 x

, so

x = 6

. The unknown resistance is

6 Ω

JEE Main · 2026 · 24 Jan 2026 · Shift 2 · Integer answer