P1.5 waves

P1.5 waves

1. KEYWORD: Amplitude- the difference from the resting place to the crest.

   • g
   • KEYWORD: wave length- the length of a full cycle of the wave (from crest 1 to crest 2)
     • KEYWORD: Frequency- the number of complete waves passing a certain point per second (measured in herts Hz) 1 Hz is one wave per second

2. DIFFERENT TYPES OF WAVE

   • Transverse waves
     • The vibrations are perpendicular (at 90 degrees) to the direction of energy transfer in the wave
     • Examples: light and all other EM waves, ripples on water, waves on strings
   • Longitudinal waves
     • The vibrations are parallel to the direction of energy transfer of the wave
     • Examples: sound waves and ultra sound, shock waves e.g. seismic waves, a slinky when you push the end

3. Wave speed = frequency x wave length

4. All waves can be reflected, refracted and diffracted

   • When waves arrive at an obstacle (or meet a new material) their direction of travel can be changed
     • REFLECTION of light lets us see things
       • When light travelling in the same direction reflects off an uneven surface the light reflects off it at different angles
       • when light travelling in the same direction reflects from an even surface then it is all reflected at the same angle so it is a clear reflection
         • That is why you can see your self in a mirror (as it is an even surface) but you cant see your self in a piece of paper, as it is an uneven surface
       • the LAW OF REFLECTION
         • Angle of incidence = Angle of reflection
     • REFRACTION changes direction when it meets a new material
       • waves are only refracted if they meet a new medium at an angle
         • If they are travelling along the normal (if it hits face on) they will change speed but are not refracted therefore they don't change direction

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