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Physics Paper 1: P1 (Waves transfer energy (All waves have amplitude,…
Physics Paper 1: P1
Waves transfer energy
All waves have amplitude, frequency and wavelength
Digital and analogue signals are used for communication. Morse is a digital code. Digital signals allow many signals to be transmitted at the same time. Digital signals are clearer.
Laser light is single colour and in phase. Laser light, visible light and infrared are all used to send signals along optical fibres by total internal reflection.
Radio waves, microwaves, infrared, visible light and ultraviolet are some of the waves in the electromagnetic spectrum. The energy of the wave increases as the wavelength decreases. All electromagnetic waves can be reflected, refracted and diffracted.
Microwaves can be used for cooking and for communication when transmitter and receiver are in line of sight.
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Energy transfer
Energy saving in the home can be achieved by:- double glazing, cavity wall insulation, draught strip, reflecting foil, loft insulation, curtains, careful design.
Air is a good insulator and reduces energy transfer by conduction. Conduction in a solid is by the transfer of kinetic energy
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Trapped air reduces energy transfer by convection. Convection currents are caused by density changes.
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Heat and temperature
Temperature is a measure of hotness on an arbitrary scale, measured in degrees centigrade. Energy is a measure of energy transfer on an absolute scale measure in J.
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Energy is transferred when a substance changes state. The amount of energy transferred depends on the mass and the specific latent heat.
Energy is transferred when a substance changes temperature. The amount of energy transferred depends on the mass, temperature change and specific heat capacity.
The stable earth
Earthquake waves travel through the Earth. Different waves help us find out about the inside of the Earth.
Exposure to ultraviolet radiation causes sun burn and skin cancer. Sunscreen and sunblock reduces damage caused by ultraviolet radiation. CFCs are causing the ozone layer to become thinner.