Waves Flashcards
what do all waves do?
transfer energy from one place to another
transverse waves (2)
- the movement (oscillations) is 90 degrees (perpendicular) to the direction the wave travels
- the movement is up and down and the direction is sideways
examples of transverse waves (2)
- ripples in a pond
- electromagnetic waves
longitudinal waves (3)
- movement (oscillations) are parallel to the direction the wave travels; they’re in the same direction as the travel
- have compressions (regions where the air particles are very close together)
- sound waves travel as particles in the air move from side to side
example of longitudinal waves
sound waves
define amplitude
the maximum displacement from rest
(the furthest point the wave vibrates from its undisturbed position)
define wavelength
the distance from a point on one wave to the equivalent point on the adjacent wave
how is wavelength measured on longitudinal waves? (2)
- by measuring from one compression to the next compression
- or by measuring from one rarefaction to the next rarefaction
define frequency
what is the unit of frequency?
the number of waves passing a point each second
hertz (Hz) ; 1 Hz = 1 wave per second
define period
the time (in seconds) for one wave to pass a point
period = 1 divided by frequency
electromagnetic waves (4)
- transverse waves
- transfer energy from the source of the waves to the absorber
- they form a continuous spectrum and all travel at the same speed in a vacuum
- the visible region of the spectrum is only a small part
the electromagnetic spectrum (2)
-
on the red end, the waves have:
1. lower frequency
2. longer wavelength -
on the violet end, the waves have:
1. higher frequency
2. shorter wavelength
what is the only part of the electromagnetic spectrum that can be detected by the human eye?
visible light
what is the order of the electromagnetic spectrum
Radiowaves
Microwaves
Infrared
Visible Light
Ultraviolet
X-Rays
Gamma Rays
radiowaves (4)
examples : tv and radio
- produced by oscillations
- in electrical circuits
microwaves (2)
examples : satellite communication, cooking food
infrared (3)
examples : IR cameras, tv remote, cooking food
visible light
examples : fibre optic communication
ultraviolet (4)
examples : sun beds, check forgeries, sterilisation (water or medical equipment)
- important due to the suns rays
x-rays (2)
examples : medical images, airport detection
gamma rays (5)
examples : medical treatments, sterilising medical equipment
- produced when there is a change in the nucleus
- measured in sieverts (Sv)
- 1000 millisieverts = 1 sievert
why does light change direction as it passes through water in a glass? (5)
- when light passes from air into glass, the velocity of light decreases
- this causes the direction of the waves to change
- the light waves now pass through the glass
- when the waves pass from the glass back into the air, their velocity increases again
- when the waves speed up, they bend away from the normal
when can refraction happen?
when any wave changes speed as it passes from one medium to another
in what case would there be no change in direction?
if the waves enter or leave the medium at right angles to the surface
how does a change to the atom generate an electromagnetic wave (2)
- when atoms are heated, electrons move from one energy level to a higher one
- when this electron returns to its original energy level, it generates an electromagnetic wave
how does a change to the nucleus generate an electromagnetic wave?
- gamma rays can be emitted from the nucleus of radioactive atoms
- once the gamma ray has been emitted, the nucleus has less energy than it had at the start
when can radiowaves be produced?
when electrons oscillate in electric circuits
