A wave in which vibrations are 90 degrees to the direction of wave travel. It features amplitude, wavelength and frequency.
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Electromagnetic Spectrum
Includes Gamma rays, X-rays, Ultra-violet, Visible Light, Infra-red, Microwaves, Radiowaves. All of them can travel through a vaccum at the speed of light.
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Reflection
Change in direction of a wave boundary between two media.
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Refraction
Change in direction of a light ray as it passes from one medium to another and changes speed.
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Diffraction
The spreading out of a wave as a result of passing an obstacle through a gap. Maximum diffraction occurs when the gap is the same width as the wavelength of the wave passes through it.
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Angle of incidence
The angle that hits the boundary
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Critical Angle
The largest incident angle at which refraction can occur.
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Total internal reflection (TIR)
This is when the angle of incidence is above the critical angle.
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Optical Fibres
Used to send information in the form of pulses of light or infrared radiation. It is a long, flexible, transparent cable, that allow fast transmission of data. Light is transmitted down by TIR.
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Wave Equation
Wave speed= Frequency x Wavelength
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Wireless Technology
Electromagnetic radiation can be used to send information without optical fibres as they can be reflected and refracted like visible light.
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Laser
Light used for communication. A laser produces a narrow, intense beam of monochromatic light (single colour).
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Laser
Lasers produce waves that have the same frequency, are in phase with each other (this means all the peaks and troughs match) and have low divergence.
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Light
Light travels fast and there is small loss of signal, however it cannot be used for wireless signalling as it doesn't diffract well.
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Electrical
Can be sent along wires, however signal deteriorates.
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Radio waves
Can be used for wireless signalling as the waves can diffract around obstacles, however the diffraction leads to signal loss.
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Electromagnetic Radiation
The amount of radiation that is absorbed or emitted. Colour- black is good, white and silver are poor and Texture- dull is good, shiny is poor
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Microwaves
Absorbed by water and fat molecules causing them to heat. They penetrate about 1cm into food. They are reflected by shiny metal surfaces, can travel through glass and plastic and burn skin when absorbed by tissue. Also used in phones and satellites.
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Infrared
Used to heat(cooking) and used for remote controls. Absorbed by shiny surfaces.
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Other cards in this set
Card 2
Front
Includes Gamma rays, X-rays, Ultra-violet, Visible Light, Infra-red, Microwaves, Radiowaves. All of them can travel through a vaccum at the speed of light.
Back
Electromagnetic Spectrum
Card 3
Front
Change in direction of a wave boundary between two media.
Back
Card 4
Front
Change in direction of a light ray as it passes from one medium to another and changes speed.
Back
Card 5
Front
The spreading out of a wave as a result of passing an obstacle through a gap. Maximum diffraction occurs when the gap is the same width as the wavelength of the wave passes through it.
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