Frequency
Higher frequency = high sound =
More waves = shorter wavelength
• Low frequency = Low sound
=Less waves= longer wavelength
Period of a Wave
• The period is the duration of one
cycle in a repeating event.
• Frequency is a measure of the
number of occurrences of a
repeating event per unit time.
Vibrations
• Sound is caused by vibrations
• Sound requires a medium (does not
happen in outer space since it is a
vacuum.)
• Sound will travel through water at 20
degrees Celsius slower than water at
80 degrees Celsius.
Energy
• The amount of energy a wave has
determines it’s amplitude.
Sound
• The unit used to measure sound
intensity is the decibel.
• Pitch is how high or low a sound
seems to be.
• When a person moves toward a
sound, the compressions of the wave
are pushed together.
Frequency
• The frequency at which a string
vibrates is its natural frequency
• The frequencies of an
instrument’s tone that are
multiples of the fundamental
frequency are overtones.
Instruments
• Brass and wind instruments make
sounds by vibrating a column of
air.
• Beats are produced by 2 sound
with different frequencies
FM
• FM broadcasting is a broadcast
technology invented by Edwin
Howard Armstrong
• FM carrier wave frequencies vary
from 88 Mhz to 108 Mhz
• FM = Frequency Modulation
Radio
• Each radio station broadcasts on one
frequency called a carrier wave.
• Information can be added to a radio
carrier wave by frequency modulation
and amplitude modulation.
Sound
• Violins, harps, and guitars produce
sound by vibrating strings.
• A flute player changes the length of a
column of air by opening and closing
holes which helps make each
different sound.
Formulas
Formula Practice
• The frequency is 30. What is the
period of the wave.
1/30
The period is 10, what is the
frequency of the wave?
1/10