Electromagnetic Induction

Topics in this chapter

• Magnetic Flux and Faraday's Law
• Motional and Rotational EMF
• Lenz's Law and Eddy Currents
• Self-Inductance and LR Circuits
• Mutual Inductance and Coupled Coils
• Inductor Energy and Combinations
• Induced Electric Fields

Cheat sheet

Practice questions

1. Question 1Q-B264BE

   A circular loop of radius $r$ is placed in a uniform magnetic field $B$ perpendicular to the plane of the loop. If the radius of the loop starts shrinking at a constant rate $dr/dt = v$, then the induced emf in the loop at that instant is:

   1. A.2\pi Brv
   2. B.\pi Brv
   3. C.Brv
   4. D.0
   See the answer and solution
2. Question 2Q-2B4DC8

   A metal rod of length $l$ is rotated with an angular velocity $\omega$ in a uniform magnetic field $B$, about an axis passing through one end and perpendicular to the rod, with the field also parallel to the axis of rotation. The induced emf across the ends of the rod is:

   1. A.\frac{1}{2} B \omega l^2
   2. B.B \omega l^2
   3. C.2 B \omega l^2
   4. D.0
   See the answer and solution
3. Question 3Q-74A6A3

   The self-inductance of a coil of 500 turns is 50 mH. When a current of 2 A flows through it, the total magnetic flux linked with each turn of the coil is:

   1. A.$2 \times 10^{-4}\text{ Wb}$
   2. B.$10^{-3}\text{ Wb}$
   3. C.$5 \times 10^{-3}\text{ Wb}$
   4. D.$2.5 \times 10^{-4}\text{ Wb}$
   See the answer and solution
4. Question 4Q-45501A

   Lenz's law of electromagnetic induction is a consequence of the law of conservation of:

   1. A.Charge
   2. B.Momentum
   3. C.Energy
   4. D.Magnetic flux
   See the answer and solution
5. Question 5Q-32190A

   Two coils, 1 and 2, have a mutual inductance $M = 1.5\text{ H}$. If the current in coil 1 changes from 0 to 20 A in 0.5 s, what is the magnitude of the induced emf in coil 2?

   1. A.30 V
   2. B.60 V
   3. C.15 V
   4. D.45 V
   See the answer and solution