# Chapter 4: Waves

- Created by: Benbingham
- Created on: 16-01-20 15:28

View mindmap

- Waves
- Waves and vibrations
- Types of waves
- Longitudinal
- Direction of vibration is parallel to direction of movement
- Examples: sound waves and P-waves

- Transverse
- Examples: S-waves and waves on a string
- Direction of vibration is perpendicular to movement of wave

- Longitudinal
- Polarisation
- Plane polarisation
- Transverse waves are plane polarised- meaning the vibrations stay in one plane.
- Longitudinal waves cannot be polarised

- Light from a filament lamp or candle is unpolarised
- This light can be polarised through a polaroid filter.
- These filters block all light except in one direction.

- This light can be polarised through a polaroid filter.

- Transverse waves are plane polarised- meaning the vibrations stay in one plane.
- Unpolarised light
- Has light travelling at all angles between 0 and 360 in a circle
- If passed through one filter it becomes polarised
- If passed through another filter the light intensity changes based on the angle of the filters
- At 90 or 270 the filters are out of phase and produce no light.
- At 0, 180 or 360 the filters are in phase and produce a full light.
- Any angle in between produces a dimmer light

- This light can be polarised through a polaroid filter.
- These filters block all light except in one direction.

- If passed through another filter the light intensity changes based on the angle of the filters

- If passed through one filter it becomes polarised

- Has light travelling at all angles between 0 and 360 in a circle

- Plane polarisation

- Types of waves
- Measuring waves
- Key terms
- Cycle
- From peak to peak or maximum displacementto maximum displacement

- Wavelength
- The least distance between two adjacent points

- Period
- The time for one complete wave to pass a fixed point

- Amplitude
- The maximum displacementa vibrating particle
- For transverse this is the height of the wave

- The maximum displacementa vibrating particle
- Frequency
- The number of cycles of vibrations of particle per second. Unit: Hz

- Displacement
- its distance and direction from equilibrium position

- Cycle
- Phase difference
- Measured in phi
- Is the fraction of a cycle it has completed since the start of the cycle
- In degrees 1 cycle = 360
- In radians 1 cycle = 2pi
- Phase difference
- Measured in phi
- Is the fraction of a cycle it has completed since the start of the cycle
- In degrees 1 cycle = 360
- In radians 1 cycle = 2pi

- In radians 1 cycle = 2pi

- Phase difference

- In radians 1 cycle = 2pi

- Key terms
- Wave properties
- Reflection
- A wave that is directed at a flat surface reflects off at the same angle- angle of reflection

- Refraction
- When a wave approaches a boundary the leading wavefront slows down earlier causing it to bend and slow down

- Diffraction
- Occurs when waves spread out after passing through a gap or around an obstacle
- The longer the wavelength also means waves spread out more
- Narrow gap means more spread out waves

- Narrow gap means more spread out waves

- The longer the wavelength also means waves spread out more

- Occurs when waves spread out after passing through a gap or around an obstacle
- Superposition
- When two identical waves meet they pass through each other
- When two peaks meet they create a super crest which is a combination of their amplitudes
- When two troughs meet they create a super trough which is a combination of their amplitudes
- When a peak meets a trough they cancel

- When two identical waves meet they pass through each other

- Reflection
- Stationary waves
- Formed when two progressive waves pass through each other
- The first harmonic is the first loop of a stationary wave
- The length of the first harmonic is half of the wavelength as only one loop is formed
- Nodes are points of a stationary wave that doesn't move
- Antinodes are points on the wave that are at maximum displacement

- Antinodes are points on the wave that are at maximum displacement

- Progressive waves
- These are waves that have no fixed points and travel freely
- Stationary waves
- Formed when two progressive waves pass through each other
- The first harmonic is the first loop of a stationary wave
- The length of the first harmonic is half of the wavelength as only one loop is formed
- Nodes are points of a stationary wave that doesn't move

- Waves and vibrations

## Comments

No comments have yet been made