User's Manual

109

012-05892A AC/DC Electronics Laboratory

Experiment 20:

Induction – Magnet Through a Coil

EQUIPMENT NEEDED:

– Computer and Science Workshop™ Interface

– Voltage Sensor (CI-6503)

– AC/DC Electronics Lab Board (EM-8656)

– Alnico bar magnet (EM-8620)

– OPTIONAL: Photogate (ME-9204A or ME-9498)

Purpose

This experiment shows the Electromotive Force (EMF) induced in a coil by a magnet dropping

through the center of a coil.

Theory

When a magnet is passed through a coil there is a changing magnetic flux through the coil which

induces an Electromotive Force (EMF) in the coil. According to Faraday’s Law of Induction:

=−N

∆

∆t

where ε is the induced EMF, N is the number of turns of wire in the coil, and

∆ φ

∆ t

is the rate of

change of the flux through the coil.

In this experiment, a plot of the EMF vs. time is made and the area under the curve is found by

integration. This area represents the flux since

∆t =−N∆

PROCEDURE

PART I: Computer Setup

➀ Connect the Science Workshop interface to the computer, turn on the interface, and turn on the

computer.

➁ Plug the DIN plug of the Voltage Sensor into Analog Channel A.