Procedure
and Tasks
1. Measure induced electro-motive force and the terminal
velocity with the oscilloscope. This is most conveniently done by using the
short Cu tube. One should connect the two coils (in parallel) to the
oscilloscope and then drop the magnet down the tube. The oscilloscope will
measure the induced voltage as a function of time. Use this plot to determine
if there is any difference in the strengths of the different magnets by
checking the maximum value of the voltage and the terminal velocity.
2. Use a 4-point contact method for measuring the
conductivity of the short tube.
3. Determine dipole moment strength from induction signal
(Again use position of the maximum).
4. Determine dipole moment strength from the terminal
velocity.
5. Measure the force between two dipole moments as a
function of separation distance. This can be performed with the aid of a
digital scale. Plot the force as a function of distance.
6. Determine dipole moment strength from the force
between the two (identical) dipoles.
7. Cool short tube with liquid nitrogen and check for any
qualitative differences in the behavior of the experiment. Such as the new
terminal velocity.
Oscilloscope operating instructions
1. Connect the pickup coils on the metal tube to the
oscilloscope.
2. Turn on the oscilloscope. Make sure every switch is on
the right position as the graph shows. In particular the input has to be on
dc-voltage.
3. Press "store" button on upper-right corner
of the front panel to display a continuous line. (If no display, try to adjust
the bean intensity).
4. Drop the magnet into the vertical tube. Press the
"save/continue" button on the top-right corner when both of the two
pulses are shown on the screen. Adjust the voltage scale (vertical axis) or the
time scale (horizontal axis) if necessary.
5. To measure the voltage amplitude or the time
difference, use the cursors on the top of the panel.
6. Press "save/continue" button again to
continue the experiment.
7. In the Mode function, choose: CH1, NORM, ALT.
8. Set time scale "SEC/DIV" in range 0.1 ~0.5s.
9. Set the voltage range of Channel 1: CH1
"VOLTS/DIV" to 5mV.
10. When the pulse signal appears, press
"save" in "ACQ" function to catch the signal.
11. In cursor function, press "on" to activate
cursors. Press "ΔV1/ΔV1" to measure voltage difference. Or
press "ΔT/1/ΔT" to measure time difference. Two measure
lines will appear on the screen.
12. Adjust the knob on the left side of the cursor
function to move the cursor line. Press this knob to select active cursor.