P11 - waves Flashcards
what are mechanical waves
waves that travel through a medium
examples of mechanical waves
sound waves, water waves, seismic waves
what are electromagnetic waves
waves that travel through a vacuum and don’t require a medium
examples of electromagnetic waves
light waves, radio waves and micro waves
does the substance move when waves travel through it (does the water move when an object is dropped in it
no, waves travel across the surface but the water does not travel away from the object.
what type of waves are electromagnetic waves
transverse waves
where are the oscillations in relation to direction of energy transfer on a transverse wave
perpendicular
what type of waves can mechanical waves be
both transverse and longitudinal
where are the oscillations in relation to direction of energy transfer on a longitudinal wave
parallel.
what type of waves are sound waves
longitudinal
how do sound waves work
when an object vibrates on the air, it makes the air around it vibrate as it pushes and pulls through the air. These oscillations (compressions and rarefactions) are sound waves
what is amplitude
maximum displacement of a wave from its undisturbed position (from the middle to the top of the wave)
what is the trough
the bottom of the wave
what is the peak/crest
the top of the wave
what is the wavelength
the distance between 2 same points of the wave (peak to peak)
what does amplitude show
the bigger the amplitude the more energy a wave has
what is the frequency
the number of waves passing a fixed point in a second
what is a peroid
the time taken for the wave to pass a fixed point in a second.
what is the equation for peroid
peroid,t (sec) = 1 / frequency(Hz)
what is the equation for wavespeed
wave speed ,v m/s = frequency, f Hz x wavelength m
what is the speed of waves
the distance travelled by each wave every second through a medium.
why do we see things from far away before we hear them
speed of light is quicker than the speed of sound.
what are plane waves
straight waves`
what is refraction
where waves change the direction they travel when they cross boundary between one medium and another
what is an incident wave
the initial wave
what happens to waves at a non zero angle to the boundary
the waves change their speed and direction when they cross the boundary
what happens to waves at a perpendicular boundary
the waves do not change direction however their speed changes.
what happens to the amplitude of waves when they pass through a substance
it gets smaller as the substance absorbs some of the energy.
what is the speed of sound waves in air
340m/s at 15 degrees.
what is an echo
reflected sound
what is the equation for the time of an echo
speed,s = distance to wall and back, 2d / time, t
can sound waves travel through a vacuum
no
how do you investigate waves
use a ripple tank for water waves
a stretched string for waves in a solid
a signal generator and a loud speaker for sound waves
