3.1 General Wave Properties Flashcards
What is a wave?
A regular disturbance transferring energy in the direction of the wave’s propagation without transferring matter.
What is a transverse wave?
A wave in which oscillations are at right angles (perpendicular) to the direction of motion.
Give examples of transverse waves
Waves on a string, all electromagnetic waves (eg. visible light), ripples on water, vibrations on guitar strings
What is a longitudinal wave?
A wave where the oscillations are parallel to (in the same direction as) the direction of motion.
Give examples of longitudinal waves
Pulses along a spring, sound waves, ultrasound
Transverse waveforms have…
Peaks and troughs
Longitudinal waveforms have…
Compressions (particles pushed together) and rarefactions (particles moved apart)
Wavelength is…
the distance between a point on one wave and the same point on the next wave (eg. Peak to peak)
measured in metres (m)
Displacement is…
• The distance from equilibrium position
• At maximum distance (peaks or troughs), this is the amplitude (the maximum displacement of the wave)
Frequency is…
+ its equation
-The number of complete waves passing a given point per second, or the number of waves per second produced by the source.
-Measured in Hertz (Hz)
-Freq = 1 / time in seconds
State the wave equation for wavespeed
v = λ x f
• v = velocity (m/s)
• λ = wavelength (m)
• f = frequency (Hz)
What is refraction?
Refraction is the change in speed of a wave when crossing a boundary between two media, resulting in a change in direction.
Which property of a wave is not changed by refraction?
The frequency.
What happens when waves are incident on a flat surface?
.
Reflection
A stronger reflected wave is produced when…
The surface is smoother.
Why do rough surfaces appear matt when illuminated?
The reflected rays light are scattered in all directions.
When entering a denser material, light waves…
..slow down and bend towards the normal.
When entering a less dense material, light waves…
…speed up and bend away from the normal.
What is diffraction?
The spreading out of waves passing through a narrow gap or across an edge.
What size of gap produces the largest diffraction?
A gap of the same width as the wavelength of the wave passing through it.
What is a ripple tank?
A shallow glass tank with an oscillating paddle/needle to create waves. It is illuminated from above so waves can be seen on the surface below the tank.
Describe how to demonstrate reflection using a ripple tank.
Waves will reflect off the glass sides of the tank.
Describe how to demonstrate refraction using a ripple tank.
Place a glass box across half of the floor of the ripple tank. The waves will change speed when travelling through the less dense area.
