Flashcards
Physics Unit 1 - Waves
Cards in this deck (20)
- 1What are the different parts of a wave?-the crest is the top of the wave, its highest point
-the trough is the bottom, its lowest point
-the amplitude is from the rest to the crest OR trough (eg height from the line through the middle)
wavelength is from crest to crest or trough to trough. - 2describe transverse waves- slinky type waves
-they are perpendicular to the direction of energy transfer
- Light and all other EM waves are transverse. - 3describe longitudinal waves- the lines type one
- they are parallel to the direction of energy transfer
they are sound waves and shock waves
- when the lines are spaced out it is called a rarefaction
-when the lines are closed it is called a compression - 4how do you work out wave speed?frequency x wave length
- 5Describe reflection:- Light bounces of our eyes to see objects.
-when light hits an uneven surface it is reflected in all directions but when it hits a smooth surface like a mirror it is a clear reflection and the angle is the same. - 6How do we see objects in a mirror?light hits the mirror at the angle of incidence, this is going towards the mirror, then it hits the normal, a line which is perpendicular to the mirror. Then at the same angle as incidence, the angle of reflection, reflects the light ray and hits our eyes so we can see it. angle of incidence = angle of reflection
- 7describe diffractiondiffraction is when an obstacle gets in the way of waves and they have to bend around it. The wave bends more if the gap is smaller, it usually becomes rounded and looks more like a Wi-Fi symbol if the gap is smaller
- 8describe refractionthis is when a wave crosses a boundary between 2 substances, say glass to air, it changes direction.
If the wave faces the substance change face on then it stays in the same direction but if the change is at an angle then the wave becomes refracted. Like when light travels through the window it gets refracted. If travelling along the normal they will NOT be refracted - 9Describe the EM spectrumRauls Mother Is Visiting Uncle Xaviers Garden
10^4m - 10^-15m in wavelength.
The shorter the wavelength the bigger the frequency. - 10Describe Radiowaves- about 10cm, but long ones can be 1-10km, they can diffract (bend) around the earth to send communication signals.
The diffraction effect makes it possible for radio signals to be received over hills and in tunnels. TV and FM radio waves have 10cm- 10m length as they are local. However short waves can be received at long distances as they are reflected by the ionsphere (the earths charged layer) but this depends on conditions of the day like weather. - 11describe microwavesThese are used for communications to satellites (like in mobiles).
Microwaves are used as the pass through the watery atmosphere, radio waves cannot do this.
For a tv the transmitter is transmitted into space where a satellite picks it up and sends it back down to earth in a different direction where a satellite dish picks it up . - 12What are some uses of microwaves?mobile phones use them to travel as microwaves to the nearest transmitter, microwaves are absorbed by water and heat them up, this is why water inside a phone is dangerous.
Remote sensing satellites are used to "see" through clouds to monitor oil spills, track icebergs movements and see how much the rainforrest has been chopped down etc - 13Describe Infared Wavesthey are used in wireless remote controls for TVs and can send different commands, by emitting different patterns.
They are also used in optic fibers to carry data over long distances. The signal is carried as pulses and is reflected of the narrow core from one end of fibre to the other. - 14Describe Visible Lightused in photography, camera lenses focus visible light into film, the lens can control how much light enters the camera (like a pupil in an eye) the shutter speed determines how long that light is exposed, by varying these you can decide how much light is going to be in a photo.
- 15Describe sound wavesThey are vibrations that are passed through mediums, they travel best through denser objects so they are heard best through solids, then liquids and worst through gases, they cant travel in space because there are no particles.
- 16Sound waves reflection and refractionThey are reflected best by hard flat surfaces, in empty rooms you hear echos better because there is no furniture to absorb the sound waves. There is a delay between the original sound and the echo because the echo waves have longer to travel to your ears. They change material through different objects, if it is more dense they speed up however as the waves always spread its hard to notice and hear this.
- 17How is pitch affected by wave frequencyhigh frequency = high pitch
low frequency = low pitch. The loudness depends on the amplitude, the bigger it is the louder the sound. This is measured in Hz. - 18Explain red shiftWhen things are further away eg in space we see the colours different and so the colours shift along moving close to red, like hearing a car vroooom it sounds lower further away.
- 19Explain the Doppler Effectwhen the frequency of a wavelength is moving towards you it sounds higher, but further away it sounds lower. Like the vrooooom of a car. We dont notice any change when the car is stationary because the waves are equally spaced.
- 20Is the Galaxy moving further away?Measurements of red shift show that further away galaxies are moving further away quicker than galaxies closer to us. This is because they have greater red shift then nearer ones. This provides evidence that the whole universe is expanding
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- GCSE Science (Physics Core) Flashcards on Physics Unit 1 - Waves, created by pwincessria on 11/04/2015.
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