EXPERIMENT 62
62
4
5
6
WHAT’S HAPPENING
The heart of this system is the electromagnet,
which attracts the metal strip when the current is
flowing. But because that would be hard to hear,
the paper contacts the rotating propeller to pro-
duce a humming sound. So you hear the dots
and dashes as short and long voice-like noises.
Of course, you shouldn’t operate this Morse
code system too long, since the motor would
soon use up the battery.
HERE’S HOW IT CONTINUES
Attach a piece of tape to each of the bare sur-
faces of the horseshoe electromagnet poles (fig-
ure 4). This will prevent the metal strip from
sticking to them after you switch off the current.
Now mount the hanger base on the cardboard
such that the metal strip swings a few millime-
ters in front of the poles of the horseshoe elec-
tromagnet, as shown in figure 5. Test to see if the
strip moves toward the magnet when you press
the push button, and that it swings back again
when you let go.
Secure the motor with its two I-connectors to the
cardboard near the end of the metal strip (figure
6). Tape a narrow strip of paper to the end of the
metal strip, so that it just barely touches the yel-
low propeller when attracted by the magnet.
Now switch on the motor and push the button in
Morse-code rhythm. What do you hear?
Summary of Contents for Electricity and Magnetism 620417
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