A rectangular loop of width w, length l and resistance R moves with constant speed v through a uniform magnetic-field region of width 3w. Which option correctly describes magnetic flux, induced emf and external force versus distance travelled?

Options

• Option A

  Flux changes linearly only during entry/exit; induced emf is constant in magnitude during entry/exit and zero while fully inside; external force opposes motion only during entry/exit.

• Option B

  Flux is constant throughout; emf and external force are always zero.

• Option C

  Flux changes quadratically; emf increases linearly while inside; external force is constant everywhere.

• Option D

  Flux changes linearly throughout the entire 3w region; emf never becomes zero.