Answer: (1/2)BL 2 omega.
- A BLomega
- B (1/2)BL<sup>2</sup> omega
- C BL<sup>2</sup> omega
- D BL omega/2
Correct answer: B. (1/2)BL<sup>2</sup> omega
Explanation: EMF of rotating rod = (1/2)BL<sup>2</sup> omega. Derived by integrating motional EMF: E = integral(0 to L) B x (omega r) dr = (1/2)B omega L<sup>2.</sup>
As a magnet approaches a coil, flux rises steadily and a constant non-zero EMF is induced (Faraday's law). Once the magnet stops moving, flux stays constant and the induced EMF drops to zero - EMF only exists while flux is actively changing.
Concept context
Faraday's and Lenz's laws, motional EMF, self/mutual inductance, eddy currents, and the AC generator - how a changing magnetic flux creates an electric current.