Question

A conducting circular loop (radius shrinking at 1 mm/s) is in a uniform magnetic field B = 50 mT, plane perpendicular to the field. Find the induced emf when the radius is 4 cm.

• A. π µV
• B. 2π µV
• C. 4π µV
• D. 8π µV

Hint:

Faraday's Law and flux through a loop

Answer 1

The Correct Option is C

Faraday's Law: emf = -dΦ/dt. Φ = Bπr². emf = -B(2πr)(dr/dt) = -(50 x 10⁻³)(2π)(4 x 10⁻²)(-1 x 10⁻³) = 4π x 10⁻⁶ V = 4π µV