1.what are the 7 types of electromagnetic waves starting with the shortest wave length?
2.who discovered infrared? when? how?
3.who discovered uv? when? how?
1.radio waves, microwaves, infrared, visible light, UV, X-rays, gamma rays.
2.by herschel in 1800. he measured the temperature just past red of the spectrum, he found it had the highest temperature of all.
3. by ritter in 1801. he used silver chloride (which turns black when exposed to light), and he placed it just past the violet part of the spectrum, here it changed the quickest of all.
4.how are microwaves harmful?
5.how is infrared harmful?
6.how is UV harmful?
7.how are gamma/x-rays harmful?
4. they have similar frequency to the vibrations of molecules, therfore holding mobile phone(which use microwaves) close to your brain. can heat human body cells and may be linked to brain tumours. but nothing has been proved.
5. they can make the surface molecules of any substance vibrate.and this has a heating effect, it has a higher frequency than microwaves, so it carries more energy. so for the human body, too much infrared can cause skin burns.
6. has more energy than infrared, and higher frequency. its ionising, so it has enough energy to knock electrons off atoms. sun burn happens when surface skin cells absorb UV rays in sunlight. this an cause cell mutation or destruction.and skin cancer. can also lead to eye damage.
7. very high frequency waves. they are also ionising, and carry more energy than UV rays.this means they can be much more damaging and penetrate further into the body. this can lead to cell mutation or destruction leading to tissue damage or cancer.
8. uses of radio waves?
9. uses of microwaves?
8. - can be used to broadcast tv and radio signals. - longwave radio, long wave lengths bend around the surface of the earth. - shortwave radio, short wavelengths reflected by the ionosphere, same with medium-wave signals. - some very short-wave radio can pass through the ionosphere and be used for satelite communications.
9. - communications to and from satelittes. - for satellite tv, the signal from a transmitter is transmitted into space,where its picked up by a satellite reciever dish orbitting the earth, then the satellite transmits the signal back in different directions. - mobile phone signals also travel as microwaves.
question 10- 12
10. how can infrared be used to monitor temperature?
11. how do optical fibres work?
12. infrared uses aroung the home?
10. - infrared is also know as heat radiation, it is given out by all hot objects. so, it can be used to monitor temperatures.eg, heat loss through a house can be detected using infrared sensors. - infrared is also detected by night vision equipment. it is turned into an electrical signal and displayed on a screen. police and military use these.
11. optical fibres can carry data over long distances as pulses of infrared radiation.they work by bouncing waves of the sides of a thin inner core of plasic or glass. the wave enters the fibre and is refleced repeatedly until it emerges at the other end.
12. - cooking(toaster and grills) - remote controls - transmit info between computers or mobiles (0nly short distance) - security systems.
13. uses of visible light?
14. uses of UV?
15. uses of X-rays?
13. we need visible light to see. we only see objects be cause they are illuminated, they either give out or reflect light. cameras work the same ways as eyes.