Electromagnetic Induction

Question 1

What are Faraday’s laws of electromagnetic induction?

Answer 1

Faraday’s laws of electromagnetic induction state:

First Law: A change in the magnetic flux through a coil induces an electromotive force (emf) in the coil.

Second Law: The magnitude of the induced emf is proportional to the rate of change of magnetic flux.
Formula:
emf = − 𝑑Φ / 𝑑𝑡
​where Φ is the magnetic flux.

Question 2

What factors affect the induced emf?

Answer 2

Factors affecting the induced emf include:

• Rate of change of magnetic flux: Faster changes induce a greater emf.
• Number of turns in the coil: More turns increase the induced emf.
• Magnetic field strength: A stronger magnetic field results in a greater induced emf.
• Area of the coil: Larger coil areas increase the flux and hence the emf.*

Question 3

What is Lenz’s Law and how does it illustrate the principle of conservation of energy?

Answer 3

Lenz’s Law states that the direction of the induced current is such that it opposes the change in magnetic flux that produced it. This illustrates the principle of conservation of energy by ensuring that the induced emf works against the change that caused it, thus conserving energy.

Question 4

How do A.C. generators work?

Answer 4

An A.C. generator (alternator) converts mechanical energy into electrical energy by rotating a coil in a magnetic field. As the coil rotates, the magnetic flux through it changes, inducing an alternating emf due to Faraday’s Law.