STANDARD Physics Induced EMF and Current MCQ Question
A circuit area 0.01 m² is kept inside a magnetic field which is normal to its plane. The magnetic field changes from 2 tesla to 1 tesla in 1 millisecond. If the resistance of the circuit is 2 Ω, the rate of heat evolved is
5 J/s
50 J/s
0.05 J/s
0.5 J/s
Correct Answer
Detailed Explanation
The induced emf is calculated using Faraday's law: ε = -dφ/dt. The change in magnetic flux is (0.01)(2 - 1) = 0.01 Wb, and the time is 1 ms = 1 x 10⁻³ s. Thus, ε = 10 V. Using V = IR, the current I = 5 A. The rate of heat evolved is I²R = (5)² x 2 = 50 J/s.
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