What is a wave?
The transfer of energy from one place to another without transferring any material
How can you tell the waves carry energy? (three-ways)
Electromagnetic waves cause things to heat up X-rays and gamma rays can cause ionisation Loud sound can make things vibrate
What is the definition of displacement?
How far are point on a wave have moved from its undisturbed position
What is the definition of amplitude?
The maximum magnitude of the displacement
What is the definition of wavelength?
The length of one whole wave cycle eg. crest to crest
What is the definition of a period of a wave?
The time taken for a whole cycle to complete
What is the definition of frequency?
The number of cycles per second passing a given point
What is a wave phase?
A measurement of the position of a certain point along the way cycle
What is the definition of phase difference?
The amount one way lags behind the other. It is measured in degrees or radians
How do you measure wavelength on a longitudinal wave?
You measure compression to compression or rarefaction to rarefaction
What is the formula that links frequency and wave period?
What is the equation that links wave speed frequency and wavelength?
Tony is using an oscilloscope. He sees a wave on this oscilloscope. What is this displayed wave called?
What does an oscilloscope display?
Waves from a signal generator as a function of voltage over time
Gertrude is using an oscilloscope. She cannot read the time Dials clearly. Suggest how she could get an accurate measurement from her oscilloscope.
Gertrude could adjust the gain dial and the time base dial to make the wave easier to measure
How can you measure sound waves?
You can plug a microphone into an oscilloscope
What is a transverse waves?
A way that oscillate perpendicular to the direction of wave propagation
What is a longitudinal wave?
A wave that oscillate parallel to the direction of wave propagation
What are the two main ways of drawing transverse waves?
Displacement against distance Displacement Against Time
How can we draw a longitudinal waves?
By plotting displacement Against Time
What is the definition of intensity?
The rate of flow of energy per unit area perpendicular to the direction of travel of the wave.
What are the units of intensity?
What is the formula that links intensity power and area?
What is the formula that links intensity and amplitude?
What properties do all the electromagnetic waves have in common?
They all travel at the same speed in a vacuum They all carry energy They can all be polarised They can all be refracted, reflected and diffracted
Jenny is trying to create a polarizing filter for sound. Explain why this is impossible?
Polarisation can only happen for transverse waves sound is a longitudinal wave
What will happen if you have 2 polarising filters at right angles to each other?
No light will get through
What is plane polarisation?
Polarising a wave so that it only oscillates in One Direction
What is the definition of polarisation?
Restricting the oscillation of a transverse wave to One Direction
Can you polarise microwaves?
Yes, as they are a transverse wave