Waves Flashcards
What type of wave is on the surface of water?
Transverse waves, particles in the water move up and down as a waves oases - the particles are not carried to the shore
How do transverse waves move?
The particles move up and down at right angles to the direction the wave is moving
What can sound waves also do?
Transfer energy
What type of waves are sound waves?
Longitudinal waves, particles in the material through which the wave is travelling move backwards and forwards as the wave passes
What type of waves do earthquakes and explosions produce?
Seismic waves, they travel through the earth.
What waves can push and pull solid rock material?
Longitudinal seismic waves
What waves can can move solid rock material up and down and side to side?
Transverse seismic waves
What are electromagnetic waves?
Light, radio waves, microwaves, they are transverse waves and do not need a medium (material) through which to travel
What is wave frequency and what is it measured in?
Frequency Is the number of waves passing a point each second, it’s measured in hertz (Hz)
For sound and light what does the frequency determine?
Sound - pitch
Light - colour
What is a period?
The length of time it takes one wave to pass a given point
What’s a wavelength?
If the distance from a point on one wave to a point on the same position on the next wave measured in meters
What’s an amplitude?
It’s the maximum distance of a point on the wave away from its rest position, measured in meters. The greater the amplitude of a sound wave, louder the sound
What is a velocity?
It is the speed of the wave in the direction it is travelling. Waves travel at different speeds in different materials
Where do you measure the amplitude?
The amplitude of a wave is from the middle to the top or bottom, not the distance between top and bottom
What can changes in frequencies, wavelengths or amplitude be used for?
Can be used to transfer information from one place to another. E.g when you listen to FM radio, the music is sent by variations in the frequency of the radio waves
Go to book and look at page 50 for wave speeds
Now
What does the speed of a wave depend on?
The medium through which its travelling
What speed does light always travel at?
300 000 000m/s in a vacuum, but it travels more slowly in glass or water.
What reduces when light goes from air into water?
The wavelength
How can you find the speed of sound?
By measuring the time it takes for a sound to travel a certain distance. For example, if you stand in front of a large wall you can measure the time it takes for an echo of a loud sound to reach you.
What can you use to calculate the speed of sound?
A Speed, time, distance equation
How can you measure the speed of waves on water?
Measure the time it takes for a wave to travel between two fixed points such as buoys. The speed can be calculated from the time and the distance between the points
Go to page 52 and 53 to look at the core practical
Now
Where do most waves travel but then where can they change direction to?
Outwards from their source in straight lines, however waves can change direction when they can move into a different medium
What is the change in direction called?
Refraction
When does refraction happen?
At the interface (boundary) between the two media
What is the line at right angles to the interface called?
The normal line
What does light travelling along the normal do?
It doesn’t change direction when it goes into a different medium
When do we see things?
We see things when light reflected from them reaches our eyes
Waves can travel through many different media but with different speeds
As light passes the interface between one medium and another it changes speed. This change in speed causes the direction of the light to change
What does the bend depend on?
How fast the light travels in the two media and the angle of the light hitting the interface. The greater the difference in speed between the two media, the more light is bent. The light bends towards the normal when it slows down
How can we use waves on water?
To help us understand what happens with light waves .
What does the speed of waves depend on?
How deep the water is
Hat do waves moving from deep water into shallow water do?
Slows down and changes direction