Electromagnetic Induction Examples in Physics

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Electromagnetic Induction.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Physics.

Concept Recap

The process by which a changing magnetic flux through a conducting loop produces a voltage (electromotive force, EMF) across the conductor, which can drive an.

Push a magnet into a coil and current flows — the changing magnetic field 'induces' electricity. Pull it out and current flows the other way.

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: A changing magnetic field creates an electric field, and vice versa — this is the link between electricity and magnetism.

Common stuck point: It's the change in flux that matters — a constant magnetic field through a stationary coil induces nothing.

Sense of Study hint: When solving an electromagnetic induction problem, first determine what is changing: the magnetic field strength, the area of the loop, or the angle between the field and the loop. Any of these changes will alter the magnetic flux \Phi_B = BA\cos\theta and induce an EMF. Then apply Faraday's law and use Lenz's law to find the direction of the induced current.

Worked Examples

Example 1

easy
A single loop of wire with area 0.05 \text{ m}^2 is in a magnetic field that changes from 0.8 \text{ T} to 0.2 \text{ T} in 0.3 \text{ s}. What is the induced EMF?

Solution

  1. 1
    Change in magnetic flux: \Delta\Phi = \Delta B \times A = (0.2 - 0.8) \times 0.05 = -0.03 \text{ Wb}.
  2. 2
    Induced EMF (Faraday's law, N = 1): \mathcal{E} = -\frac{\Delta\Phi}{\Delta t} = -\frac{-0.03}{0.3} = 0.1 \text{ V}
  3. 3
    The magnitude of the induced EMF is 0.1 \text{ V}.

Answer

\mathcal{E} = 0.1 \text{ V}
Electromagnetic induction occurs whenever the magnetic flux through a conducting loop changes. The induced EMF is proportional to the rate of change of flux, as stated by Faraday's law.

Example 2

medium
A coil with 200 turns and area 0.02 \text{ m}^2 is rotated from perpendicular to parallel to a 0.5 \text{ T} magnetic field in 0.1 \text{ s}. What is the average induced EMF?

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

medium
A bar magnet is pushed into a coil of 100 turns, increasing the flux through each turn from 0 to 0.004 \text{ Wb} in 0.2 \text{ s}. What is the induced EMF? If the coil has resistance 5 \text{ } \Omega, what current flows?

Example 2

hard
A rectangular loop (0.1 \text{ m} \times 0.2 \text{ m}) moves at 5 \text{ m/s} into a region with a uniform 0.3 \text{ T} magnetic field. What EMF is induced as the loop enters the field?
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Background Knowledge

These ideas may be useful before you work through the harder examples.

magnetic fieldmagnetic force