Faraday's Law Physics Example 3

Follow the full solution, then compare it with the other examples linked below.

Example 3

medium
A coil of 5050 turns has an area of 0.01 m20.01 \text{ m}^2. The magnetic field through it decreases from 0.8 T0.8 \text{ T} to 0.2 T0.2 \text{ T} in 0.5 s0.5 \text{ s}. What is the average induced EMF?

Solution

  1. 1
    Change in flux per turn: ΔΦ=(0.2−0.8)×0.01=−0.006 Wb\Delta\Phi = (0.2 - 0.8) \times 0.01 = -0.006 \text{ Wb}.
  2. 2
    Induced EMF: E=−NΔΦΔt=−50×−0.0060.5=0.6 V\mathcal{E} = -N\frac{\Delta\Phi}{\Delta t} = -50 \times \frac{-0.006}{0.5} = 0.6 \text{ V}

Answer

E=0.6 V\mathcal{E} = 0.6 \text{ V}
The induced EMF is proportional to the rate of change of flux and the number of turns. Lenz's law tells us the induced current opposes the change that caused it.

About Faraday's Law

The induced EMF in a circuit equals the negative rate of change of magnetic flux through the circuit.

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More Faraday's Law Examples

Example 1 medium

A coil with [formula] turns experiences a change in magnetic flux from [formula] to [formula] in [fo

Example 2 hard

A single loop of area [formula] is in a magnetic field that increases uniformly from [formula] to [f

Example 4 medium

A coil of [formula] turns has a magnetic flux that changes from [formula] to [formula] in [formula].

Example 5 hard

A square coil with 200 turns and side length [formula] is in a magnetic field that decreases uniform

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