How do waves behave? Flashcards
What do all waves have?
frequency - the number of waves that pass at a fixed point per second (this is measured in hertz (Hz)
amplitude - the maximum displacement that any particle achieves from its position in metres (m)
wavelength - the distance from one point on a wave to the equivalent point on the next wave in metres
period - the time take for one complete oscillation in seconds (s)
What are two types of waves?
transverse and longitudinal waves
What do all waves do?
transfer energy from one place to another
for example -
if a stone is dropped into a pond, ripples travel outwards carrying the energy - the water does not travel outwards.
What do the particles that make a wave do?
they oscillate (vibrate) at a fixed point. they pass the energy on to the next particles, which also oscilate
the energy moves along but the matter remains (stays)
What happens during a transverse wave?
e.g. in a water wave, the oscillations (vibrations) are perpendicular (at right angles to the direction of energy being transferred
this can be shown by moving a rope up and down vertically - the wave then moves horizontally
What happens during a longitudinal wave?
e.g. sound wave, the oscillations are parallel to the direction of energy transferred which can be shown by moving a spring moving back and forward horizontally - the wave will also move horizontally
What are sound waves?
vibrations from a source pass into a material nearby and travel through as sound waves
What do sound waves do?
they travel more easily through solids and liquids than through gases
sound waves can reach our ears by travelling through air
they are longitudinal waves
the speed of sound in air is about 330-340 m/s
What is the wave speed?
the speed at which energy is transferred (or the waves move)
it is a measure of how far the waves move in one second and can be found with the wave equation
What is the wave equation?
wave speed (m/s) = frequency (Hz) x wavelength (m)
What are ripples on the surface of water?
slow enough that speed can be measured by direct observation and timing with a stopwatch
How does the speed and wavelength of waves change?
as they are transmitted from one medium to another
e.g. water waves travelling from deep to shallow water
What happens as wave’s speed changes?
it goes through refraction
What is refraction?
involves a change in direction of travel of the waves
the frequency does not change because the same number of waves is still being produced by the source per second
all waves obey the wave equation, the speed and wavelength are proportional
Doubling the speed….
doubles the wavelength
