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MHT CET 2025 (19 Apr, Shift 2) · Magnetic Flux & Faraday's Law

Magnetic Flux & Faraday's Law question from MHT CET 2025 (19 Apr, Shift 2)

Q30MHT CET 2025 · 19 APR · SHIFT 2Medium

Magnetic Flux & Faraday's Law

The magnetic flux through a coil is 4×10−4 Wb4 \times 10^{-4}\text{ Wb} at time t=0t = 0. It reduces to 30%30\% of its original value in time tt second. If e.m.f. induced in the coil is 0.56 mV then the value of tt is

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Answer: (a)

  1. Flux falls to 30%30\%, so Δϕ=0.7×4×10−4=2.8×10−4\Delta\phi = 0.7 \times 4 \times 10^{-4} = 2.8 \times 10^{-4} Wb.
  2. e=Δϕt⇒t=Δϕee = \frac{\Delta\phi}{t} \Rightarrow t = \frac{\Delta\phi}{e}
  3. t=2.8×10−40.56×10−3=0.5t = \frac{2.8 \times 10^{-4}}{0.56 \times 10^{-3}} = 0.5 s
  4. So the answer is (a) 0.5 s.
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