Can you differentiate transverse and longitudinal wave in AS/A-level Physics?

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 2^nd 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.

• Glare reduction
• TV and radio signals improvement

• 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!

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