Vibration – a wiggle in time For example: moving back and forth in the same space, ie ., pendulum. **A vibration exists over time .* *. Wave – a wiggle in space and time For example : light and sound **A wave exists over space and time **. Major parts of a wave:.
Vibration – a wiggle in timeFor example: moving back and forth in the same space, ie., pendulum. **A vibration exists over time.**
Crest (high point)
Trough (low point)
how often a vibration occurs
(# of crests per second)
vibrations per second
Heinrich Hertz demonstrated radio waves in 1886.
The unit of frequency is the Hertz.
1 vibration per second = 1 Hertz
Kilohertz= 1000 v/sec
Megahertz= 1000000 v/sec
How does a radio work?
When you create a wave with a rope, it is the disturbance that moves along the rope, not the rope itself.
How fast a wave moves depends on the medium of the wave.
v = f*
Wave speed (m/s) =
frequency (Hz) X wavelength (m)
What is the speed of a wave with a frequency of 100 Hz and a wavelength of .025 meters?
v = fλ
Speed = 100 Hz X .025 m
Speed = 2.5 m/s
How does satellite tv work?
Waves produced when the motion of the medium is at right angles (PERPENDICULAR) to the direction in which the wave travels.
EX: Fishing bobber in a lake
Waves produced when the particles move ALONG (PARALLEL) the direction of the wave rather than at right angles to it
EX: Sound Waves
Interference Patterns: patterns formed when waves overlap
when waves align at the crests and troughs
**individual effects are increased**
when the crest of one wave aligns with the trough of another
**their individual effects are reduced**
Blue shift = frequency increases as it approaches
Red shift = frequency decreases as it leaves
A slower aircraft sends sound wave crests one at a time and we hear it as a continuous noise.
All sounds are made by the vibration of material objects.
term that refers to how high or low sound appears to be
Is it possible to shatter glass with your voice?
high frequency = high pitch
Lower # of vibrations =
lower frequency = lower pitch
20 - 20,000 Hz
Ultrasonic – sound waves above 20,000Hz
Infrasonic – soundwaves below 20 Hz
Any medium that waves travel through; may be solids, liquids or gases
Usually, sounds are emitted through air, but they can also pass through solids and liquids
EX: ever heard motor boats under water?
EX: lightening and thunder
Resonance– a phenomenon that occurs when the frequency of forced vibrations on an object matches the object’s natural frequency, and a dramatic increase in amplitude results
Resonance can occur in structures
EX: marching over bridges
swinging bridges by wind
Interference occurs in sound waves.
Interference can occur “in phase” (constructive) or “out of phase” (destructive)
EX: announcer at a football stadium
Beat – periodic variation in the loudness of sound (different frequencies)
EX: musical instruments out of tune
What is the beat frequency when a 400 Hz and a 405 Hz tuning fork are sounded together?
Change in frequency = 5 Hz
Therefore, the beat frequency is 5 beats per second
Speed of light = extra distance traveled
extra time measured
= 300,000,000 km / 1000 sec
= 300,000 km/sec
light year – the distance traveled by light in one year
≈ 9.5 x 1012 km
Light waves are transverse waves.
Polarization – the filtering out of all vibrations in a transverse wave, such as a light wave, that are not in a given direction