Physics: waves,Sound

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Waves use repeated vibrations (oscillation) to carry energ. They do not carry matter.
Frequency is the nubmer of complete waves per second. freaquency is measured in "hertz" Hz. 1Hz=1 wave per second
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Electromagnetic spectrum is a group of 7 waves which have similar properties: transvers, can travel through space (vacuum), travel at the speed of light (300000000m/s)
Herschel and IR: 1.He shone sunlight through a glass prism to form a colour spectrum. 2. thermometers were placed in each colour to measure the tempurature 3. the tempurature went higher as it went from blue to red
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4. a thermometer was placed placed beyond red and the tempurature was even higher. Herschel had discovered Infra-red.
(Joham)Ritter and UV: Ritter saw Herschels experiment and decided to test the region beyond violet. He placed silver chloride in the spectrumand noticed a bigger effect (darkening) as he moved from red to blue.
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The greatest effect occured beyond violet. Ritter had discovered Ultra-Violet.
EM waves Hazards: Radio- No known harm; Microwaves- 12cm wavelength causes water to heat up and can cause cataracts; Infra-Red- causes blisters and burns to surface layers; Light- bright light can damage the retina;
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Ultra-violet- Skin cancer and damage DNA, Sunburn , Eye damage; X-rays- low doses cause cancer and large doses kill cacerous cells; Gamma rays- same as X-rays.
EM wave uses: Radio- telecomunication (radio, TV), give info about space; Microwaves-12cm wavelength microwaves make water molecule vibrate and heat up so they can be used for cooking, carrying mobile phone or satellite tv signals, find rain clouds
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Infra-red- cooking in normal ovens, blue-tooth signals, heat cameras(burglar alarms, fire services); Ultraviolet- Sun beds, hardening polymers(e.g dentistry), security checks (e.g fluorecent writing on bank notes), kills bacteria;
X-rays - take x-ray photo`s, to kill cancer cells (large doses, radiotherapy); Gamma-rays same as x-rays but more powerful. sterolizing food and medical instruments.
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[radiation is energy carried by waves or or particles] Refraction: when any wave crosses through a boundry of media (substance) there is usually a achange of speed due to the different density which results in a change of direction , called refration
The only time the wave would not change direction is if it travels alomg the normal (90 degrees).
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Sound: sound is caused by vibrations and is carried through media (substances) by longitudional waves. sound can not pass through vacuum (space). People have the ability to hear sound from 20Hz to 20000Hz
Below 20Hz is called infr-sound and higher than 20000Hz is called Ultr-sound.
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The tone is called the pitch which increases with frequency. the loudness is determined by amplitude and the distance from the source.
Sonar: Sonar uses uktrasound as it is able to travel further and is a more targetted beam than ordinary souund.
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Other cards in this set

Card 2

Front

Herschel and IR: 1.He shone sunlight through a glass prism to form a colour spectrum. 2. thermometers were placed in each colour to measure the tempurature 3. the tempurature went higher as it went from blue to red

Back

Electromagnetic spectrum is a group of 7 waves which have similar properties: transvers, can travel through space (vacuum), travel at the speed of light (300000000m/s)

Card 3

Front

(Joham)Ritter and UV: Ritter saw Herschels experiment and decided to test the region beyond violet. He placed silver chloride in the spectrumand noticed a bigger effect (darkening) as he moved from red to blue.

Back

Preview of the back of card 3

Card 4

Front

EM waves Hazards: Radio- No known harm; Microwaves- 12cm wavelength causes water to heat up and can cause cataracts; Infra-Red- causes blisters and burns to surface layers; Light- bright light can damage the retina;

Back

Preview of the back of card 4

Card 5

Front

EM wave uses: Radio- telecomunication (radio, TV), give info about space; Microwaves-12cm wavelength microwaves make water molecule vibrate and heat up so they can be used for cooking, carrying mobile phone or satellite tv signals, find rain clouds

Back

Preview of the back of card 5
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