Waves

Question 1

What are waves

Answer 1

Waves transfer energy without transferring matter

Waves are described as oscillations or vibrations about a fixed point

Question 2

Features of a wave

Answer 2

Crest (Peak) - highest point of the wave
Trough - lowest point of the wave
Amplitude - the length from the highest point to the normal
Wavelength - from one crest/ trough to another crest/trough
Frequency - the number of waves passing a point in a second (measured in hertz)
Wave speed -the speed at which energy is transferred through a medium
Wavefront - useful way to show how longitudinal waves are seen
When the wave fronts are closer it means they have a shorter wavelength

Question 3

Wave speed equation

Answer 3

Frequency (f) x wavelength (Hz) = wave speed (m/s)

Question 4

How to work out a period (time period) (for frequency)

Answer 4

T = 1/f

T = seconds
f = frequency

Question 5

Transverse features and examples

Answer 5

Waves where the points along its length vibrate at 90 degrees to the direction of energy transfer

Examples
- seismic waves
- water waves
- electromagnetic radiation

Transverse features
- the energy transfer is in the same direction as the wave motion
- can move in a liquid or a solid not in a gas
- the curve are drawn so that they are perpendicular to the direction of energy transfer

Question 6

Longitudinal waves

Answer 6

Waves where the points along its length vibrate parallel to the direction of energy transfer

Examples
- seismic P waves
-sound waves

Longitudinal waves features
- The energy transfer is in the same direction as the wave motion
- They can move in solids, liquids and gases They can move in solids, liquids and gases
- They can not move in a vacuum

Close together, called compressions they have a high densities and high pressures
Spaced apart, called rarefactions they have low densities and low pressures

Question 7

Reflection of a wave

Answer 7

Angle of incidence = angle of reflection
Frequency remains the same
Wavelength remain the same
Direction is different
You can use a ripple tank to demonstrate this

Question 8

Refraction

Answer 8

When waves go thru different medium it changes speed

The wavelength can increase/decrease
Can also change direction

Usually water waves are slower in more shallow areas they bunch together therefore wavelength decreases so will wave speed (if in deep vice versa)

Frequency remains the same

Question 9

Diffraction

Answer 9

When the waves go into a gap/ or around an object

If the gap is the same size as the wave length the wave makes a circular in a shape

If the gap is bigger, wavelength and speed remains the same, the waves bend around the obstacle when it goes through a gap making the waves kinda rectangular

The smaller the opening the larger the diffraction will be the greater the wave front the diffraction will be more too