School of Physics Lecture Demonstration Manual

Eb-2 Faraday's Law of Induction

Published: Tuesday 14 March 2006 - Updated: Tuesday 29 March 2011

Aim

To demonstrate the generation of an EMF in a coil threaded by a changing magnetic field.

Apparatus

Diagrams

Click on pictures to enlarge.

Faradyas Law of Induction Diagram 1

Faraday's Law of Induction Diagram 2

Description

1) A coil (A) is connected to the galvanometer set to its second most sensitive scale. A small magnet is brought into the centre of the coil, held stationary there and then withdrawn. The deflections in each case are noted; only relative motion produces a deflection.

2) The magnet is taken away and replaced with the circuit shown below. Coil B must be placed as close to coil A as possible and the sensitivity of the galvanometer increased to maximum.

Deflections are noted on closing or opening the switch but not while there is a steady current in the circuit.

At this stage some lecturers might like to introduce the concept of permeability by placing a thick iron bar so as to thread coils A and B. The deflections are increased on repeating the experiment.

Safety notes

Electrical safety 

Maintenance 

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