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CUET · PHYSICS · PYQ PAPER 2025

A long solenoid with 25 turns per cm has a small loop of area \( 2.0 \text{ cm}^2 \) placed inside the solenoid normal to its axis. If the current carried by the solenoid changes steadily from 3.0 A to 5.0 A in 0.1 s. The induced emf in the loop due to change in the current is

  1. A \( 4\pi \times 10^{-8} \text{ V} \)
  2. B \( 4\pi \times 10^{-7} \text{ V} \)
  3. C \( 4\pi \times 10^{-6} \text{ V} \)
  4. D \( 4\pi \times 10^{-4} \text{ V} \)
Verified Solution

Answer & Solution

Correct Answer

(C) \( 4\pi \times 10^{-6} \text{ V} \)

Step-by-step Solution

Detailed explanation

\( n = 25 \text{ cm}^{-1} = 2500 \text{ m}^{-1} \) \( A = 2.0 \text{ cm}^2 = 2.0 \times 10^{-4} \text{ m}^2 \) \( \frac{dI}{dt} = \frac{5.0 \text{ A} - 3.0 \text{ A}}{0.1 \text{ s}} = 20 \text{ A/s} \) \( \mathcal{E} = A \mu_0 n \frac{dI}{dt} \)…