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P1 Glossary AW
Glossary of key words for P1- Energy for the Home
| Term | Definition |
|---|---|
| Amplitude | The maximum displacement of a point on a wave from its rest position. |
| Analogue signal | A signal that shows a complete range of frequencies; sound is analogue. |
| CFCs | Gases which used to be used in refrigerators and which harm the ozone layer. |
| Conductors | Materials which transfer thermal energy easily; electrical conductors allow electricity to flow through them. |
| Critical angle | Angle at which a light ray incident on the inner surface of a transparent glass block just escapes from the glass. |
| Diffraction | A change in the directions and intensities of a group of waves after passing by an obstacle or through an opening whose size is approximately the same as the wavelengths of the waves. |
| Digital signal | A signal that has only two values- on and off. |
| Efficiency | Ratio of useful energy output to the total energy input; can be expressed as a percentage. |
| Electromagnetic spectrum | Electromagnetic waves ordered according to wavelength and frequency- ranging from radio waves to gamma rays. |
| Endoscope | Device using optical fibres which allows doctors to look inside the human body. |
| Energy | The ability to “do work”- the human body needs energy to function. |
| Finite resource | Resources such as oil that will eventually run out. |
| Fossil fuels | fuels such as coal, oil and gas. |
| Frequency | The number of waves passing a set point per second. |
| Gamma rays | Ionising electromagnetic waves that are radioactive and dangerous to human health- but useful in killing cancer cells. |
| Hertz | Units for measuring wave frequency. |
| Infrared waves | Non-ionising waves that produce heat- used in toasters and electric fires. |
| Insulation | A substance which reduces the movement of energy; heat insulation in the loft of a house slows down the movement of warmth to the cooler outside. |
| Insulator | A material that transfers thermal energy only very slowly. |
| Interfere | Waves interfere with each other when two waves of different frequencies occupy the same space; interference occurs in light and sound and can produce changes in the intensity of the waves. |
| Ionosphere | A region in the Earth’s atmosphere where ionization caused by incoming solar radiation affects the transmission of radio waves; it extends from 70km (43 miles) to 400km (250 miles) above the surface. |
| Joule | A unit of energy. |
| Kinetic energy | The energy that moving objects have. |
| Laser | A special kind of light beam that can carry a lot of energy and can be focussed very accurately; lasers are often used to judge the speed of moving objects or the distance to them. |
| Latent heat | The energy needed to change the state of a substance. |
| Light emitting diode (LED) | A very small light in electric circuits that uses very little energy. |
| Longitudinal wave | In longitudinal waves, the vibration is in the same direction in which the wave travels. |
| Microwaves | Non-ionising waves used in satellite and mobile phone networks- also in microwave ovens. |
| Morse code | A code consisting of dots and dashes that code for each letter of the alphabet. |
| Multiplexing | Combination of multiple signals into one signal transmitted over a shared medium. |
| Non-renewable energy | Energy which is used up at a faster rate than it can be replaced, e.g. fossil fuels. |
| Optical fibre | A flexible optically transparent fibre, usually made of glass or plastic, through which light passes by successive internal reflections. |
| Ozone layer | Layer of the Earth’s atmosphere that protects us from ultraviolet radiation. |
| p wave | Longitudinal seismic wave capable of travelling through solid and liquid parts of the Earth. |
| Payback time | The time it takes for the original cost outlay to be recovered in savings. |
| Phase | Fraction of a complete wave that one wave disturbance is different to another. |
| Power | The rate that a system transfers energy, power is usually measured in watts (W). |
| Radiation | Thermal energy transfer which occurs when something is hotter than its surroundings radiates heat from its surface. |
| Radio waves | Non-ionising waves used to broadcast radio and TV programmes. |
| Receiver | Device which receives waves, e.g. a mobile phone. |
| Refraction | When a light ray travelling through air enters a glass block and changes direction. |
| Renewable energy | Energy that can be replenished at the same rate as it is used up, e.g. biofuels. |
| s wave | Transverse seismic wave capable of travelling through solid but not liquid parts of the |
| Earth. | |
| Seismic wave | Vibration transmitted throuth the Earth. |
| Seismometer | A device used to detect movements in the Earth’s crust. |
| Specific heat capacity | The amount of energy needed to raise the temperature of 1kg of a substance by 1 degree Celsius. |
| Specific latent heat | The amount of energy needed to change the state of a substance without changing its temperature; e.g. the energy needed to change ice at 0 degrees Celsius to water at the same temperature. |
| Stratosphere | A layer in the atmosphere starting at 15km above sea level and extending to 50km above sea level; the ozone layer is found in the stratosphere. |
| Temperature | A measure of the degree of hotness of a body on an arbitrary scale. |
| Themogram | A picture showing differences in surface temperature of a body. |
| Total internal reflection | The reflection of light inside an optically denser material at its boundary with on optically less dense material (usually air) |
| Transmitter | A device which gives out some form of energy or signal, usually used to mean a radio transmitter which broadcasts radio signals. |
| Transverse wave | In transverse waves, the vibration is at right angles to the direction in which the wave travels. |
| Ultraviolet radiation | Electromagnetic waves given out by the Sun which damage human skin. |
| Watt | A unit of power, 1 watt equals 1 joule of energy being transferred per second. |
| Wavelength | Distance between two wave peaks. |
Created by:
Brimsham
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