P1.2 The EM Spectrum
- Created by: SanaaM
- Created on: 25-02-16 20:36
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- P1.2 The EM Spectrum
- 1.Infrared and Ultraviolet
- IR Radiation was discovered by Herschel - he found temperatures increased beyond the red end
- Wavelength of IR is longer than visible light
- The frequency of IR is lower than visible light
- UV Radiation was discovered by Ritter - Rate of reaction of silver chloride increased most beyond violet.
- The wavelength of UV is shorter than visible light
- The frequency of UV is is higher than visible light
- IR Radiation was discovered by Herschel - he found temperatures increased beyond the red end
- 2. EM Waves
- Properties of EM Waves = all transverse, can travel through medium, travel at same speed as light
- Can transfer energy NOT matter
- Can be reflected, refracted or diffracted
- EM Spectrum Mnemonic - Radioactive Mice Invade Venus Using X-Ray Guns
- Properties of EM Waves = all transverse, can travel through medium, travel at same speed as light
- 3. Uses of EM Waves
- Visible Light - photography, vision, illumination
- UV - Security (as absorbs UV and remits Visible Light, kill bacteria, used to disinfect sewage/water
- X-Rays - Security (scanners used in airports, detect broken bones
- Radio Waves- detected by aerials,TV and radio broadcasts, communicatin
- IR - object give out IR (even us) Rescue service use it to find survivors under rubble , cook food (toasters)
- Microwaves- cook for, communication with mobile phones.
- Gamma Rays - Sterilizer food(kill of bacteria), removes germs from medical instruments, detects and treats cancer
- 5. Ionising Radiation
- Alpha Particles
- Beta Particles
- Gamma rays
- 4. Dangers of EM Waves
- Microwaves- cause internal heating of body cells (water)
- IR - absorbed by skin(feel heat), too muchcan damage cells/burn skin
- X-Rays - carry a lot of energy, excess exposure can cause genetic mutation cancer)
- UV - damage DNA, exposure to sun=skin cancer, damage eyes (cataracts)
- 1.Infrared and Ultraviolet
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