Teaching Modern Physics - QuarkNet - Fermilab

Notes on the Electron PowerPoint Presentation
What is a Cathode Ray?
Streams of electrons issuing from the cathode of an evacuated tube.
Demos for Three Experiments in One
For Path A*
Equipment: Scotch® Magic Tape
To do: 1. Remove a 10 cm tape from the roll. Fold over a tab to make a handle.
Secure the tape to the table.
2. Create a second tape of equal length with a handle. Place the tape on
top of the first piece so that it covers the length of the first piece of
tape. Remove both pieces of tape from the table simultaneously. Rip
the pieces apart CAREFULLY!
3. Repeat the first two steps so that now you have four tapes.
4. Bring each of these tapes together and discover the interactions.
(Similar tapes should be repelled and opposite tapes should attract.)
5. Record your observations.
*Similar to AAPT’s “String and Sticky Tape Labs” by Ron Edge
For Path C
Equipment: Strong U-shaped magnet; direct current in a wire produced by the
application of an electric potential.
To do: 1. Connect approximately 1 m of wire to a DC outlet.
2. Place the wire through the arms of the magnet so that the current flows
in one direction perpendicular to the magnetic field produced by the
poles of the magnet.
3. Apply an electric potential to the wire and observe the behavior of the
wire. (The wire should be pushed up or down.)
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