Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
21 Cards in this Set
- Front
- Back
|
All EM waves are .. |
TRANSVERSE WAVES |
|
|
All EM at what speed? |
The same speed, (3 x 10*8 m/s) = in a vacuum eg. space |
|
|
EM waves with Higher Frequencies have ... |
Shorter Wavelengths eg. X-rays and Gamma rays |
|
|
Name the Waves in order.. Increasing F and decreasing Wavelength |
Radio waves Micro waves Infra- red Visible light Ultra Violet X-rays Gamma Rays |
|
|
Infra-red was discovered by who? |
William Herschel in 1800 Found: when experimenting with sunlight in a prism. White light = when goes through the prism creates a spectrum of colours. Wanted to know about the about of heat, measured temp. Noticed, increased - violet to red - highest temp = infa-red |
|
|
Who discovered Ultra-Violet? |
Ritter, in 1801. Found: Knew that Silver Chloride turned white from black when exposed to light. Measured how quickly Silver Chloride coated strips - changed when exposed to different colours of light. In a dark room created a spectrum, using a light source exposed the strips to each colour Violet part of the spectrum - quickest change of all |
|
|
The higher the Frequency .. |
the more energy, the more harmful radiation |
|
|
Microwaves ... |
similar frequency to vibrations of molecules, results in heating - microwave ovens Heat human body cells this way, mobile phones, concern as held close to brain - brain tumour link |
|
|
Infra-red .. |
Range of frequencies - make the surface molecules vibrate = heating effect Higher F then microwaves = carries more energy, too much exposer to radiation = SKIN BURNS |
|
|
Ultra-Violet.. |
More Energy - higher F - IONISING - carries enough energy to knock electrons off. SUNBURN - when surface skin cells = damaged Cell mutation/destruction, skin cancer, eye-damage |
|
|
Gamma Rays and X-rays |
Very High Frequency - IONISING Much more damaging - carry more energy = penetrate further into body. Cell mutation/destruction - leading tissue damage/cancer |
|
|
Radio Waves .. |
TV and Radio signals - transmit satellite signals. |
|
|
Microwaves are used for Satellite Communication and Mobile Phones.... |
Communication to and from Satellites use microwaves - which pass easily through the Earth's atmosphere From Satellite TV - from a transmitter -receiver dish orbiting - satellite transmits the signal back |
|
|
Infra-red uses... |
Monitor Temperature, transmit data. Cooking - grills/toasters Remote controls - TV/DVD players Security systems |
|
|
Need visible light to .. |
see. Take photos using a camera |
|
|
Ultra-violet's uses ... |
Detect forged Bank Notes. Fluorescence - property of certain chemicals. Where UV is absorbed - Visible light is emitted Bank = fluorescent markings on their bank notes. Under UV - genuine = display the markings. Fake - will not glow. Disinfect water - UV kills off viruses/bacteria in water. |
|
|
X-rays uses ... |
X-ray 'Photographs' = easily see through flesh, but not through bone - too dense. The amount of Radiation absorbed - gives denser image. Cause cancer - radiographers wear lead apron - keep exposure to minimum Airport Security - scan - look for suspicious objects |
|
|
Gamma rays = radiotherapy |
High dose - kill all living cells, have to be directed carefully and at the right dosage, kill the cancer cells without killing too many normal ones Damage is done = patient = very ill. |
|
|
Gamma rays = Sterilisation of food and surgical instruments |
Food = exposure - kill all microbes - keeps food fresh for longer Medical instruments - in the same way Advantage = not damaged like boiling water would damage them |
|
|
Name the three types of Ionising Radiation? |
Gamma, Alpha, Beta |
|
|
When is Ionising Radiation emitted? |
All the time by radioactive sources when their nuclei decay - emission is completely random - can't predict. All transfer energy - bash into each other and knock electrons off |
