PHY_10_62_V2_P_Faraday law of induction

Lesson Objectives

By the end of the lesson learners will be able:

10.4.2.1 – to explain the occurrence of electromotive force when changing the magnetic flux;
10.4.2.2 – to explain the Lentz's law.

Size of the voltage

Direction of the voltage

Note Well

An EMF IS Induced when:

The coil is moved through the magnetic field, across the pole pieces.

OR

The magnet is moved so that the wire passes across the face of the pole pieces.

An EMF is NOT Induced when:

The wire is held stationary between the pole-pieces

The magnet is moved so that the pole –pieces move along the length of the wire

The wire moves lengthways so that it does not change its position between the poles of the magnet.

Assessment for Learning

1. Which of the following actions will induce an electromotive force (ℇ) in a conductor?
a. Move a magnet near the conductor.
b. Move the conductor near a magnet.
c. Rotate the conductor in a magnetic field.
d. Change the magnetic field strength.
e. all of the above

Assessment for Learning

2. A circular loop having10 turns with a radius of 29 cm is in a magnetic field that oscillates uniformly between 0.95 T and 0.45 T with a period of 1.00 s.
a) How much time is required for the field to change from 0.95 T to 0.45 T?
b) What is the cross-sectional area of one turn of the loop?
c) Assuming that the loop is perpendicular to the magnetic field, what is the induced emf in the loop?

Assessment for Learning

E = B L v

If the wingspan is L
E = B L v cos θ