6 - beginning of waves topic Flashcards
what do waves transfer
ENERGY
whats the amplitude of a wave
maximum displacement from the middle line
whats the wavelength of a wave
distance between the same point on two dif waves
whats the frequency of a wave
number of complete waves passing through a certain point per second - hertz
transverse waves and examples
- oscillations are perpendicular to the direction of energy transfer
- all EM waves
- ripples in water
longitudinal waves and examples
- oscillations are parallel to the direction of energy transfer
- ultrasound
- seismic waves
what are the trends of the EM spectrum
- increase in frequency (radio smallest –> gamma biggest)
- decrease in wavelength (radio biggest –> gamma smallest)
list of electromagnetic waves
- radio waves
- micro waves
- infrared
- visible
- ulta violet
- x rays
- gamma
how are radio waves made
alternating current which produces oscillating electric and magnetic fields
what are radio waves used for
COMMUNICATIONS
- long wave radio - bend around the earth’s surface -
- short wave radio - reflects off the ionosphere - Bluetooth
what are microwaves used for
COMMUNICATIONS
- to and from satellites - pass easily through Earth’s watery atmosphere
- microwaves get absorbed by watery molecules in food and transfer their energy - food heats up
what is infrared used for
- infrared cameras - detect infrared radiation and monitor temperature - by converting the radiation into electrical signals and displaying them on a screen and the hotter the object the brighter it looks
what is visible light used for
- optic fibres - thin glass/plastic fibred that carry data from telephones or computers over long distances as pulses of visible light - they use reflection to bounce back and forth
- photography
- illumination
what is ultra violet used for
- security pens - under uv light the ink will glow
- exposure will give you a suntan
- disinfection
what are x rays used for
- x ray photographs - easily pass through flesh but not bone - see if bone is broken etc
- radiotherapy - treat cancer patients - kill living cells
what is gamma radiation used for
- radiotherapy - treat cancer patients - kill living cells
- medical tracers - injected into patient and followed around the body and can pass out easily
what are the dangers of EM waves
- high-frequency waves are very bad - gamma/ultraviolet/xrays
- UV - damage surface cells - sunburn
- xrays and gamma - ionising - gene mutations/cell destruction/higher risk of cancer
specular reflection
smooth flat surface
mirror
diffuse reflection
rough surface
slight scattered in different directions
creates distorted image - ripples in atank
why does refractuon happen at the boundary between deep and shallow water
- velocity / speed is slower in shallow water
- so edge of wave (front) entering shallow water slows down
- but the part of the wave (front) in deeper water continues at a higher speed
