WAVES

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precious o

Cards (76)

what do waves do?
they transfer energy from one place to another but not matter
what are transverse waves? 
waves whose oscillations are perpendicular to the direction of the wave
what are examples of transverse waves? 
- electromagnetic waves
- ripples on water
- waves on a string
what are longitudinal waves? 
waves whose oscillations are parallel to the direction of the wave
what are examples of longitudinal waves?
- sound waves
- seismic waves
what is frequency?
number of waves passing a point each second
what is a period? 
the time for one complete wave
what is the equation for a period?
T = 1/f
what is the equation for wavespeed?
wavespeed = frequency × wavelength
what is the speed of light?
3 × 10⁸ m/s
what can happen when waves arrive at a boundary between two different materials?
- absorption
- reflection
- transmission (refraction)
what is the rule for all reflected waves?
angle of incidence = angle of reflection
when does specular reflection occur?
when waves are reflected in a single direction and the boundary is smooth
when does diffuse reflection occur? 
when waves reflected in multiple directions and the boundary is rough
what occurs during refraction?
a wave crosses a boundary and changes direction
what affects the speed of a wave passing through a material? 
the material's density
when does a wave bend towards the normal when passing through a material?
when the material has a higher density and the wave slows down
when does a wave bend away from the normal when passing through a material? 
when the material has a lower density and the wave speeds up
what happens to the wavelength if a wave slows down?
it will decrease
what are sound waves?
longitudinal waves which cause particles to vibrate parallel to the direction of wave travel
how do we hear sound?
- ear canal
- eardrum
- three small bones transmit vibrations to the cochlea
- produces electrical signals which go to the brain
what is the frequency of a sound wave related to?
pitch
what is the amplitude of a sound wave related to?
volume
what is the human hearing range?
20 - 20,000Hz
what are ultrasounds?
sound waves which have a frequency above 20,000Hz
what happens when ultrasound waves meet the boundary between two different materials?
- some are reflected
- the time taken for the waves to leave and return is measured
- the depth can be determined using the speed of sound and time taken
what are ultrasounds used for?
medical and industrial imaging
what are seismic waves?
vibrations produced by earthquakes in the earth's crust
what are the types of seismic waves? 
primary and secondary waves
what are the properties of p-waves? 
- longitudinal
- faster
- can travel through solids and liquids
what are the properties of s-waves? 
- transverse
- slower
- can only travel through solids
what are seismic waves used for? 
investigating the earth's interior structure
what do s-waves suggest about the earth?
the outer core must be liquid as it cannot be detected on the opposite side of the earth
what do p-waves suggest about the earth?
there is a solid inner core as there are two shadow zones where none can be detected
what do all electromagnetic waves do?
- transfer energy as radiation from the source of the waves to an absorber
- travel through a vacuum
- travel at the same speed
what is the mnemonic for the electromagnetic spectrum?
roman men invented very unusual x-ray guns
what are the seven electromagnetic waves in order?
- radio waves
- microwaves
- infrared
- visible light
- ultraviolet
- x-rays
- gamma rays
how does the wavelength and frequency of the electromagnetic spectrum change as you go down?
- decreasing wavelength
- increasing frequency
what are radio waves used for?
- communication
- radio
how can you produce radio waves? 
by oscillations using an alternating current in an electrical circuit