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Can you differentiate transverse and longitudinal wave in AS/A-level Physics?
Transverse and Longitudinal Wave
Transverse Wave
- It is the displacement of particles or field is at right angles to direction of energy propagation.
- All electromagnetic waves are transverse.
- It travels as vibrations through magnetic and electric fields with vibrations perpendicular to direction of energy transfer.
Longitudinal Wave
- It is the displacement of particles or fields is along direction of energy propagation.
- E.g. Sound
- Sound waves have alternate compressions and rarefactions of the medium it travels through.
- Some type of earth quake shockwaves are also longitudinal (p-waves).
Polarised Waves
- Shaking rope by moving hand up and down or side to side or in mixture directions makes transverse waves.
- But if one tries to pass rope through vertical fencing, the wave will only get through if vibrations are vertical.
- Fence filters out vibrations in other directions.
- It only oscillates in one direction.
- Light waves are mixture of directions.
- Polarised filter can polarise light waves and other waves.
- If 2 polarised filters at right angles to reach other than no light passes through.
- The 2nd filter blocks out all light when transmission axis at right angle to plane of polarisation.
- It only happens in transverse waves which provides evidence for their nature.
Uses of Polarisation
- Glare reduction
- TV and radio signals improvement
Superposition of Waves and Formation of Stationary Waves
- Stationary Waves – superposition of 2 progressive waves with same freq., WL or amplitude moving in opposite directions. No energy transmitted.
(1) First Harmonic
- It is a stationary wave vibrating at its lowest possible frequency.
- There is one loop with node at each end.
- ½ WL fits onto string so WL is double length of string.
(2) Second Harmonic
- Twice frequency of first harmonic.
- 2 loops with node at each end and middle.
(3) Third Harmonic
- 3x frequency of first harmonic.
That's the end of the topic!
Drafted by Bonnie (Physics)