waves Flashcards
what are waves
the vibration of particles from one to another
devices used to measure the speed of a wave
sensor
slow motion video playback
stopwatch
amplitude
the maximum displacement from rest
concordant
matching data
higher frequency = …
shorter wave length
frequency = …
amount of waves/time
wavelength =
distance/number of waves
angle of instance = …
angle of reflection
what happens when a light wave goes from air to water
wave slows down
refracts towards the normal
frequency does not change
what happens when a light wave goes from water to air
wave speeds up
refracts away from the normal
frequency does not change
longitudinal waves
oscilation of particles parallel to the direction of the wave
transverse wave
the vibration of particles perpendicular to the direction of the wave
what do waves transfer
energy
information
what do electromagnetic waves have in common?
travel at the same speed in a vacuum
they are all transverse waves
what does it mean when the spectrum is “continuous”
no gaps or pauses in between wavelengths
infared
used for short-range communication, e.g. remote controls
bends and stretches molecules
useful for surface heating which Is good for cooking food
causes skin burns
microwaves
microwaves are not refracted by the atmosphere, which is why they are good for satellite communication
only long microwaves can pass through the atmosphere
good for heating liquids as they only heat up moisture
rotates molecules
causes internal heating of cells
dangerous in a concentrated area
radiowaves
not used for cooking as its frequency is too low
refracted by the atmosphere
only short radiowaves get through the atmosphere
used for long-distance communication
not dangerous as frequency is too low
UV waves
damages cells
useful for killing bacteria and tanning
uv cannot get through glass or dense material
uv can go through water
explain how uv is used in a florecent lamp
the uv absorbs the white coating and emits visible light
absorbs short wavelengths
emits longer wavelengths
x rays
used for seeing bones
can damage cells
explain how xrays are used in bone scanning
bone is too dense for xrays to pass through
the dense material will absorb the xrays
less dense material will transmit xrays
gamma
can kill cancer cells
highest frequency
kills bacteria
can damage cells
why can gamma not be used for xrays
gamma rays penetrate through denser material
what types of wavelengths can pass through the atmosphere
long
where do radiowaves come from
oscilation of electrons
how do radiowaves transmit signals
a transmitter sends oscillating electrons (radiowaves)
the receiver absorbs the radiowaves and its electrons will oscillate at the same frequency
how do UV/Xrays form
electrons dropping towards the nucleus
X rays jump closer to the nucleus
how gamma radiation forms
when an unstable nucleus rearranges itself
wavespeed = …..
wavelength x frequency
what do waves not transfer
matter
explain why some telescopes are placed in space and others are placed on the earth’s surface
(6 marks)
-some stars emit em waves that carry information about them
- these waves are absorbed by the earth’s atmosphere such as UV, gamma, xrays and some microwaves
- by shooting a telescope into space, we can collect all information about the stars as they are outside the atmosphere
- they are able to detect all wavelengths for a more detailed picture
- visible and some microwaves are not absorbed
- making it unnecessary for some telescopes that only need that information to be shot into space
what happens when you shine white light at a prism
(6 marks)
-as the ray of light travels into the prism, all colours refract towards the normal
- red has the longest wavelength and will refract the normal the least and will travel the fastest
- violet has the shortest wavelength and will refract towards the normal the most and will travel the slowest
- colours will spread out as each colour moves at different speeds because of their different wavelengths
- em waves move at different speeds in denser materials as they are transverse
- colours speed up when they exit the glass
- they refract away from the normal
- all colours get back at the same speed
