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Electromagnetic induction
Class 12 · Physics · 5 questions
Name: ____________________ Date: ____________
Faraday's law says the induced emf is proportional to the:
- A Magnetic flux
- B Rate of change of magnetic flux
- C Area only
- D Resistance
Lenz's law is a consequence of conservation of:
- A Momentum only
- B Energy
- C Charge
- D Mass
A coil has 100 turns and the flux through each turn changes by 0.02 Wb in 0.1 s. The average emf is:
- A 0.2 V
- B 200 V
- C 2 V
- D 20 V
The SI unit of inductance is the:
- A Tesla
- B Henry
- C Farad
- D Weber
Energy stored in an inductor L carrying current I is:
- A L I2
- B 1/2 L I
- C 1/2 L I2
- D L I
Answer key
1. B, 2. B, 3. D, 4. B, 5. C
emf = -d(flux)/dt.
The induced current opposes the change causing it, which conserves energy.
emf = N x change in flux / time = 100 x 0.02 / 0.1 = 20 V.
Inductance is measured in henries.
U = 1/2 L I2.