The amplitude of the induced emf in
the motor-driven
coil can be used to determine the magnitude and direction of the
magnetic field
of the earth (54 uT at an inclination of 69º in Oberlin) or of the
big gray horseshoe
magnet (0.10 T at the center of the gap).
The coils have 1000 turns on a 1" square frame. The
rotation rate is 28.6 Hz.
We also
have a Rawson rotating coil
magnetometer.
NOTES
Make sure the contacts are clean,
use a shielded cable, and connect the frame of the motor to the
oscilloscope ground.
