Topic 5 Light And The Electromagnetic Spectrum Flashcards
What is refraction?
Refraction is the change in the direction of a light ray that happens when it travels from one transparent material into another. Rays of light that meet a surface at 90(degrees) do not bend at all but simply continue into the material without a change in direction
What is electromagnetic spectrum?
-travel at the same speed in a Vacuum
- transfer energy to the observer
As the frequency of the radiation increases, the wavelength decreases
Waves in the electromagnetic spectrum
Longest wavelength and lowest frequency
Radio waves
Micro-waves
Infrared
Visible light
Ultra-violet
X-rays
Gamma rays
Shortest wavelength and highest frequency
How do you investigate refraction?
Method:
1. Place the rectangular block on the A3 paper and draw around it with the sharp pencil
2. Draw the normal line, which will be at right angles to the side of the block towards which the light ray will be shone
3. Using the protractor and pencil, mark on the paper angles of incidence of 0(degrees) through 80(degrees) in 10(degree) intervals
4. Starting with the 0(degree) angle direct the light ray towards the block and mark its exit point from the block with a sharp pencil dot
5. Remove the glass block and join the dot to the point of incidence by drawing a straight line.measure and record this angle, which is the angle of refraction
What are some harmful effects on people of excessive exposure to electromagnetic radiation?
Microwaves- internal heating of body cells
Infrared- skin burns
Ultraviolet- damage to surface cells and eyes, leading to skin cancer and eye conditions
X-rays and gamma rays- mutation or damage to cells in the body
What are radio waves used for?
Including broadcasting, tv programmes, aeroplanes and satellites
What are microwaves used for?
Cooking, communications and satellite transmissions
What are infrared used for?
Cooking, thermal imaging and optical fibres
What is visible light used for?
Vision, photography and illumination
What is ultraviolet used for?
Security marking and fluorescent lamps
What are x-rays used for?
Observing the internal structure of objects and airport security scanners
What are gamma rays used for?
Sterilising food and medical equipment
