Karteikarten
Key Words and Deffinitions
Karten in diesem Stapel (31)
- 1ReflectionSound waves and light waves reflect from surfaces. When waves reflect, they obey the law of reflection:
the angle of incidence equals the angle of reflection - 2Ray DiagramsIn a ray diagram, the mirror is drawn a straight line with thick hatchings to show which side has the reflective coating. The light rays are drawn as solid straight lines, each with an arrowhead to show the direction of travel. Light rays that appear to come from behind the mirror are shown as dashed straight lines.
- 3SoundSound waves are longitudinal waves. Their vibrations occur in the same direction as the direction of travel. Sound waves can only travel through a solid, liquid or gas.
- 4VibrationsWhen an object or substance vibrates, it produces sound:
- 5The Electromagnetic SpectrumThe electromagnetic spectrum is a continuous range of wavelengths. The types of radiation that occur in different parts of the spectrum have different uses and dangers, which depend on their wavelength and frequency.
- 6Radio WavesRadio waves are used to transmit television and radio programmes. Television uses higher frequencies than radio.
- 7MicrowavesMicrowave radiation can also be used to transmit signals such as mobile phone calls. Microwave transmitters and receivers on buildings and masts communicate with the mobile telephones in their range.
- 8Visible LightVisible light is the light we can see. It allows us to communicate with one another through books, hand signals and video, for example. The use of visible light needs the transmitter and receiver to be in the line of sight. But it is more secure against eavesdroppers than radio waves.
- 9InfraredWe cannot see infrared radiation, but we can feel it as heat energy. High intensity infrared is used in heaters, toasters and grills, and it can cause burns.
- 10The Big Bang TheoryThe Big Bang Theory states that originally all the matter in the universe was concentrated into a single incredibly tiny point. This began to enlarge rapidly in a hot explosion (called the Big Bang), and it is still expanding today. The Big Bang happened about 13.7 billion years ago (that's 13,700,000,000 years using the scientific definition of 1 billion = 1,000 million).
- 11The Doppler EffectYou may have noticed that when an ambulance or police car goes past, its siren is high-pitched as it comes towards you, then becomes low-pitched as it goes away. This effect, where there is a change in frequency and wavelength, is called the Doppler effect.
- 12Red-ShiftWhen an object moves away from an observer, its light is affected by the Doppler effect.
- 13Cosmic Microwave Background RadiationThe CMBR comes from radiation created at the beginning of the universe. The Big Bang theory is the only theory at the moment that can explain the presence of the CMBR.
- 14Infrared radiationInfrared radiation is a type of electromagnetic radiation, which involves waves rather than particles. This means that, unlike conduction and convection, radiation can even pass through the vacuum of space.
- 15Kinetic theoryThe kinetic particle theory explains the properties of the different states of matter. The particles in solids, liquids and gases have different amounts of energy. They are arranged differently and move in different ways.
- 16ConductionHeat energy can move through a substance by conduction. Metals are good conductors of heat but non-metals and gases are usually poor conductors of heat. Poor conductors of heat are called insulators. Heat energy is conducted from the hot end of an object to the cold end.
- 17ConvectionLiquids and gases are fluids. The particles in these fluids can move from place to place. Convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy. Heat energy is transferred from hot places to cooler places by convection.
- 18EvaporationEvaporation involves a liquid changing to a gas
- 19CondensationCondensation involves a gas changing to a liquid.
- 20U-ValuesU-values measure how effective a material is an insulator. The lower the U-value is, the better the material is as a heat insulator.
- 21Solar PanelsSolar panels do not generate electricity, but rather they heat up water. They are often located on the roofs of buildings where they can receive heat energy from the sun.
- 22Specific Heat CapacityThe specific heat capacity of a substance is the amount of energy needed to change the temperature of 1 kg of the substance by 1°C. Different substances have different specific heat capacities.
- 23WavesWaves are vibrations that transfer energy from place to place without matter (solid, liquid or gas) being transferred.
- 24Transverse WavesIn transverse waves, the oscillations (vibrations) are at right angles to the direction of travel and energy transfer.
- 25Longitudinal WavesIn longitudinal waves, the oscillations are along the same direction as the direction of travel and energy transfer.
- 26AmplitudeThe amplitude of a wave is its maximum disturbance from its undisturbed position. Take care: the amplitude is not the distance between the top and bottom of a wave.
- 27WavelengthThe wavelength of a wave is the distance between a point on one wave and the same point on the next wave. It is often easiest to measure this from the crest of one wave to the crest of the next wave, but it doesn't matter where as long as it is the same point in each wave.
- 28FrequencyThe frequency of a wave is the number of waves produced by a source each second. It is also the number of waves that pass a certain point each second.
- 29WavespeedThe speed of a wave is related to its frequency and wavelength, according to this equation:
v (wavespeed) = f (frequency) × λ (wavelength) - 30RefractionSound waves and light waves change speed when they pass across the boundary between two substances with different densities, such as air and glass. This causes them to change direction and this effect is called refraction.
- 31DiffractionWhen waves meet a gap in a barrier, they carry on through the gap. However, the waves spread out to some extent into the area beyond the gap. This is called diffraction.
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- GCSE PHYSICS Karteikarten am Key Words and Deffinitions, erstellt von bevsb am 12/05/2013.
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