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JEE Main 2025 (28 Jan, Shift 2) · Wheatstone Bridge & Metre Bridge

Wheatstone Bridge & Metre Bridge question from JEE Main 2025 (28 Jan, Shift 2)

Q23JEE Main 2025 · 28 JAN · SHIFT 2Medium

Wheatstone Bridge & Metre Bridge

The value of current I in the electrical circuit as given below, when potential at A is equal to the potential at B, will be _______ A.

Figure

Numerical answer type. Work it out, then open the answer.

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Answer: 2

  1. VA=VBV_A = V_B: balanced bridge, 1020=R40⇒R=20 Ω\dfrac{10}{20} = \dfrac{R}{40} \Rightarrow R = 20\ \Omega
  2. No current in 30 Ω30\ \Omega. Top path 10+20=30 Ω10+20 = 30\ \Omega, bottom path 20+40=60 Ω20+40 = 60\ \Omega
  3. Req=30×6090=20 ΩR_{eq} = \dfrac{30 \times 60}{90} = 20\ \Omega
  4. I=4020=2I = \dfrac{40}{20} = 2 A
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