waves Flashcards
what is a mechanical wave
wave
must travel through substance ( medium)
examples: sound waves,seismic waves
what is an electromagnetic wave
a wave
don’t need to travel through medium (can travel through vacuum)
examples: light waves, radio waves, microwaves
KNOWN AS THE ELECTROMAGNETIC SPECTRUM
how fast do electromagnetic waves travel
300,000km per second
what is a transverse wave
a wave
vibration at right angles to the energy transfer
eg light
what is a longitudinal wave
the vibrations
parrollel to the energy transfer
eg sound
what is the amplitude of a wave
height of wave crest or depth of wave trough
what is the peak of a wave
the highest point of the wave
what is the trough of a wave
the lowest point of a wave
what is oscillation
the distance between the peak and the trough
what is the wavelength
the distance between 2 peaks or 2 troughs
what is a compression
when the wave lengths are very close together (high pressure)
what is a rarefaction
where the waves lengths are far from eachother ( low pressure)
what are waves
vibrations
transfer energy from place to place without matter being transferred
what is the frequency of a wave
the number of waves produced/pass by a source each second
measured in Hz (hertz)
what’s the human hearing range in Hz
20Hz to 20,000Hz
what is the period of a wave
the time taken for one wave to be produced/pass a point
measured in seconds
what is a wavefront
the lines we draw to represent the vibrating part of a wave
)))))))
what is diffraction
when the wave meets a gap but spread out to some extent beyond the gap
what does the extent of the diffraction depend on
on how the width of the gap compares to the wavelength of the waves
what would create a significant diffraction
large wavelength and a narrow gap
eg sound through a doorway
what would create little diffraction
wide gap with small wavelength
eg light through a doorway
how does the wavelength change with diffraction
the wavelength doesn’t change with diffraction
what is the wave equation
speed (m/s) = frequency (Hz) x wavelength (m)
v= f x /\
what is 1kHz and 1mHz equivalent to in Hz
1kHz= 1,000Hz
1mHz= 1,000,000Hz
how do you work out the frequency of a wave
frequency= 1
————
Time Period
time period is the time it takes to complete 1 oscillation (measured in seconds)
what do we use waves for
to transfer energy and information
what happens to the air particles when a sound wave passes through the the air
makes vibrations
compressions (close together) and rarefactions (spread out)
why might someone gave bad signal if they live near hills
if the radio waves don’t diffract enough
