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 29 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.
