Week 7: EM Waves
Chapter 34
Facts you may need for the Quiz:
Everything talked about in lecture
and in the book.
Concept-tests:
7.1 Transmitting a signal
7.2 E-Field and Distance
7.3 3-Polarizers
7.4 Quickest path for Lifeguard
7.5 Depth of Fish
Answers to
Concept Tests
Demos:
RADIO--By making electrons jiggle in a wire a electromagnetic wave is
generated. The wave is received in a radio, which means that electrons
in the antena of the radio are made to jiggle. The radio is tuned to
be resonant with the carrier wave. The carrier wave is modulated at a
certain frequency (I did Amplitude Modulation AM). The radio filters
out the carrier wave and you are left with the Modulating wave which
then goes to the speakers and is converted to sound.
MICROWAVE MADNESS--Used a microwave oven to demonstrate that EM waves can cause
electrons to move. This was seen as sparks on a copper scouring pad and a compact disk.
Also attempts were made to create Ball Lightning using a burning toothpick,
in this case sparks occur due to the blackened carbon on the pre-burned
toothpick.
Polaroid Sheets--demonstrated the effects of polarizing filters on the unpolarized
light coming from the overhead projector.
Links: