Section 18 - Waves and the electromagnetic spectrum - Waves, boundaries and refraction Flashcards
What happens when a wave travels through a medium?
The particles of the medium vibrate and transfer energy and information between each other
What is amplitude of a wave?
Displacement from rest position to a crest or trough
What is the wavelength of a wave?
Length of a full cycle of wave, e.g. from crest to crest
What is frequency?
The number of complete cycles of a wave passing a certain point per second. Measured in Hz
What is period and equation for it?
The number of seconds it takes for one full cycle
Period = 1 ÷ frequency
What are vibrations like in transverse waves?
Vibrations are perpendicular to the direction the wave travels.
3 examples of transverse waves?
All electromagnetic waves, S-waves (type of seismic wave) and ripples/waves in water
What are vibrations like in longitudinal waves?
Vibrations are parallel to the direction the wave travels
2 examples of longitudinal waves?
Sound waves and P-waves (type of seismic wave)
2 equations for wave speed?
Wave speed (m/s) = Distance (m) ÷ time (s) v = x ÷ t Wave speed (m/s) = Frequency (Hz) x Wavelength (m) v = f x λ
Three ways to measure speed of sound, water ripples and waves in solids?
Sound - use oscilloscope and two microphones distanced
Water ripples - Use strobe light to project ripples on screen
Waves in solids - Use peak frequency by hitting metal rod with hammer and microphone at other end
3 things that can happen to waves when they meet a boundary?
Absorbed, transmitted or reflected
What do waves transfer?
Energy from one place to another without transferring any matter
Which EM wave wavelength type bends more through a boundary?
Shorter wavelengths bend more (e.g. blue light or UV)
What happens when a wave crosses from less dense material to a denser material at an angle?
Refracts and slows down
