Users' Guide User guide

Xplorer GLX Users’ Guide 127
Activity 7: Induced Electromotive Force
Background
When a permanent magnet passes through a coil, the changing magnetic flux
induces and electromotive force (EMF) or voltage in the coil. According to Fara-
day’s Law of Induction:
where ε is the induced EMF, N is the number of turns in the coil, and is
the rate of change of magnetic flux through the coil.
In this activity, you will drop a magnet through a coil while the GLX records and
graphs the induced EMF versus Time. The area under the under the curve repre-
sents the total change in flux.
Before You Begin
Start a new experiment on the GLX.
1. Press to go to the Home Screen.
2. Use the arrow keys to highlight the Data Files icon and press to open
the Data Files screen.
3. Press to open the Files menu and press to select New File.
4. When the GLX asks if you would like to save the previous file, press
to save or not to save.
Procedure
Equipment Set-Up
1. Clamp or mount the coil so that the magnet can be dropped through it.
2. Place something soft under the coil to prevent the magnet from breaking.
3. Connect the voltage probe to the coil so that it will measure the voltage
across the coil.
Equipment Quantity
Xplorer GLX
1
Voltage Probe
1
Coil
1
1
Bar Magnet
1
1
Use a coil with a few hundred turns,
such as the one included with PASCO
part CI-6512.
ε N
dφ
dt
------
–=
dφ dt⁄
F4
1pqrs
F1
F2