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Electromagnetic spectrum (Refraction= image (Internal reflection= image…
Electromagnetic spectrum
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Uses of electromagnetic waves; radio waves= broadcasting and communications
microwaves= cooking and satellite transmissions
Infra-red= heaters and night vision equipment
visible light= optical fibers and photography
ultraviolet= florescent lamps
X-rays= observing the internal structure of the objects and materials and medical applications.
Gamma rays= sterilizing food and medical equipment.
dangers of electromagnetic waves ; microwaves= internal heating of body tissue
infra-red= skin burns
Ultraviolet= blindness
Gamma rays= cancer, mutation
Mirrors 
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Image = laterally inverted , Virtual , same distance, inside mirror
Refraction=
Refractive index=
E.g= Light enters glass an angle of 45 to the normal, and refracts to an angle of 30 . Calculate refractive index for glass.
n= sin i/ sin r = sin 45/ sin 30 = 0.707/ 0.5 = 1.41
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Internal reflection=
When light leaves glass, it bends away from the normal.
As the angle increases , The ray bends further until it bends along the side of the block .This is called critical angle.
e.g= What is the critical for Perspex, which has a refractive index of 1.4?
Sin=c 1/n = 1/ 1.4 = 0.714
Equation =
Total internal reflection=
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Prisms=
Optical fibers
Light is transmitted along optic fibers as digital signals . The light flashes on and off quickly to represent 1s and 0s . This is a binary code that represents original signal to be sent.
white light consists of many different wavelengths . Each wavelength corresponds to a different colour. Different colors have different refractive indexes. Monochromatic means light of a single color or wavelength . Mon chromatic light would not be dispersed by a prism.
Sound = They are longitudinal vibrations of air molecules . Sound does not travel in vacuum , as there are not air molecules to vibrate.
The higher the pitch , The shorter period of wave . The more an object vibrates the greater amplitude of the wave . The shape of waves indicates what was vibrating.
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