Data Sheet
-87-
165. Frequency of Sine Wave
Build the circuit shown on the left and turn on the switch (62). Turn on the
switch (62) and hold the magnet (7) near the reed switch (83) and you
will hear the alarm (78) sound. Move the magnet (7) away from the reed
switch (83) and the alarm (78) will sound for a little while and then go
off. f
c
was dened as the frequency of a sine wave in project #163. The
frequency of a sine wave represents
the number of cycles per second of
the sine wave. Higher frequency sine
waves have more cycles per second
and lower frequency sine waves have
fewer cycles per second. The gure on
the right shows various sine waves of
different frequencies.
166. Phase of a Sine Wave
Replace the 1kW resistor (42) in project #165 with the 5.1kW resistor
(43) and turn on the switch (62). Hold the magnet (7) near the reed
switch (83) and you will hear the alarm (78) sound. Move the magnet
(7) away from the reed switch (83) and the alarm (78) will sound for
a while and then go off. q was dened as the phase of a sine wave in
project #163. The phase of a sine wave represents the starting point
of the sine wave cycle. When q = 0,
the sine wave starts at 0 amplitude at
time t=0. When q=p/2, the sine wave
starts at its maximum amplitude of A
at t=0. The gure on the right shows
various sine waves of different phases.
167. Speed of Sound
Replace the 1kW resistor (42) in project #165 with the 10kW resistor
(44) and then turn on the switch (62). Hold the magnet (7) near the
reed switch (83) and you will hear the alarm (78) sound. Move the
magnet (7) away from the reed switch (83) and the alarm (78) will
sound for a several seconds and then go off. The speed of sound varies
depending on the substance it travels through. In dry air at 0 degrees
Celsius, the speed of sound is approximately 331.2 meters/s.