Term 3 Waves (Physics) Flashcards
Define amplitude
The height of the crest or trough in a wave
Define frequency
The number of cycles in a wave in a unit of time
Define light
A type of energy made of photons that moves as a transverse wave
Define a longitudinal wave
Waves where the disturbance moves in the same direction as the wave
The wave moves left to right and at the same time the disturbance moves left to right
Examples a coil spring like a slinky
Sound waves
Define sound
Vibrations that move through matter and move as longitudinal waves
Define transverse wave
Waves where the disturbance moves perpendicular (at right angles) to the direction of the wave
Wave moves left to right while the disturbance moves up and down
Example ocean wave, Mexican wave of fans in a crowd
Define wavelength
The distance between two peaks or two troughs
What is a wave
A disturbance that travels through space and matter transferring energy from one place to another
What is the highest point of a wave called
The crest
What is the lowest point of a wave called
The trough
Some every day examples of waves
Sound waves
Microwaves
Radio frequency waves
Name 4 properties scientists use describe waves
- Amplitude - shows strength of wave; measures how much waves moves from the flat or rest position
- Frequency - number of waves per second. Measures in Hertz or cycles per second
- Wavelength - distance between two corresponding parts of the wave eg crest to crest (top to top)
- Speed: time or distance covered by the wave
What is a high frequency wave
Waves with high frequency of waves (lots of waves per unit of time)
Shows on a wave graph as more squiggles!
What is a low frequency wave
Less peaks and troughs per wave cycle
- less ups and downs on the graph - more spaced out
What is a mechanical wave and how do they move
Needs a medium (matter) to travel through
Longitudinal wave
Compressional wave
Transverse wave
4 examples of mechanical waves
Sound wave
Seismic wave
Water waves
Ropes and swings
What is an electromagnetic wave
Can travel through a vacuum of empty space (don’t need matter to travel through)
Moves in traverse wave
Example if light wave
What do both waves types of mechanical waves and electromagnetic waves have in commen?
Both transmit energetic but DO NOT transmit matter
What is a SOUND WAVE and how does it start and how does it move ?
Sound wave is a vibration that travels through matter
Vibration starts with a mechanical action eg knock on door pluck guitar string
It travels in longitudinal waves
What are the 4 properties of sound?
Loudness - more amplitude means louder (taller waves from the base line)
Pitch - determined by frequency of waves. Higher pitch (high notes) higher frequency
Lept
Timbre - how pure or clear a sound is. One wave type means more pure the note
Echo - bouncing of sound waves off objects and returning to start. Hard materials cause echos while soft materials absorb sound waves
What unit do we measure the amplitude fo sound waves in?
Decibels - a loins noise has higher decibels
Human voice is around 60 decibels
Whisper is 20 decibels
Over 120 decibels like a jet plane Up close can damage hearing
Why is light unique?
Because it behaves like a particle and like a wave
What is the speed of light (the fastest speed in the universe )
3 x 10 to the power of 8 metres per second
That’s why it looks like light is instant when you flick a light switch
How is a shadow formed
When an object blocks light
The more solid the object the darker the shadow is formed.
If an object is transparent it will let light through so have a pale shadow
How do shadows change shape
Depends on the position of the light source
Lower sun in sky gives longer shadow
What makes light reflect off a surface
If the object is shiny it means it is reflecting light
What is the angle of reflection
The angle that light reflects off a surface
Flat surface means light hits the surface and is reflected away at the SAME angle
Example a mirror
What is an incident ray?
It’s reflected rays
