| Electricity and Magnetism > Magnetic Materials |
DCS# 5G40.10 |
HYSTERESIS CURVE
-
APPARATUS
toroid with ferrite core
|
214-01-G2 |
6.3 V transformer
|
107-01-C |
integrator/amplifier circuit
|
214-03-G1 |
DC
power supply
|
214-01-C
|
30
ohm and 5.6
ohm variable resistors
|
202-19-F
|
oscilloscope
with camera
|
202 |
DESCRIPTION
- The B vs H curve of the
ferromagnetic core is displayed on an oscilloscope:
.
- NOTES
- The scope should be in x-y
mode. Display the current in the
primary coil (voltage across the resistor), which is proportional to
the applied field H, on channel 1. The integrated output of
the secondary coil, which is proportional to
the magnetic induction B, is displayed on channel 2.
If using a resistor other than the 5.6 ohm rheostat, use AC coupling on
channel 1 or the curve will be distorted.
Curie temperature:
It can be shown that the magnetization
goes to zero at the Curie
temperature by heating the coil to ~ 150°C.
Heat the coil in 3 cups
of canola oil in a Fry Daddy (214-03-F). It
takes about five minutes to reach the Curie temperature.
-
REFERENCES
Chin-Shan Lue, A
Direct Method for Viewing Ferromagnetic Phase Transition, TPT 32,
304-305
(1994).