Example 1 · level 1
A metal rod 1 m long moves at 5 m/s perpendicular to a uniform 0.2 T magnetic field. Find the emf induced between its ends (in V, correct to 2 decimal places).
Show solution
- ε = 0.2 × 1 × 5 = 1 V.
Answer: 1 V
CLASS 11–12 PHYSICS · ELECTROMAGNETIC INDUCTION
Electromagnetic induction: induced emf
Faraday's law: ε = −N dΦ/dt with Φ = BA cosθ. Motional emf of a rod: ε = Blv. Self-induction: ε = −L dI/dt.
Loading practice…
Worked examples
Example 2 · level 2
A coil of 50 turns and area 0.05 m² is perpendicular to a 0.5 T field. The field is reduced uniformly to zero in 0.2 s. Find the magnitude of the average induced emf (in V, correct to 2 decimal places).
Show solution
- ΔΦ per turn = 0.025 Wb.
- ε = 50 × 0.025 ÷ 0.2 = 6.25 V.
Answer: 6.25 V
Example 3 · level 3
The current in a coil of self-inductance 0.1 H changes from 2 A to 0 in 0.01 s. Find the magnitude of the self-induced emf (in V, correct to 2 decimal places).
Show solution
- |ε| = 0.1 × 200 = 20 V.
Answer: 20 V