2259399
| Question | Answer |
| Acceleration | The rate of change of velocity, acceleration depends on the mass of the object and the force applied. |
| Alternating Current (A.C.) | An electric current that constantly changes direction. |
| Ampere | The unit of electric current. |
| Amplitude | The maximum displacement from the mean position in a transverse wave. In sound it is the measure of the loudness of the sound. |
| Big Bang | The accepted theory of how the Universe began, which states that all matter was created in an explosion from a single point in space at a single time, the matter was thrown outwards and has continued to travel outwards ever since. |
| Biofuel | Energy sources derived from recently living organic matter for example biodiesel is made from vegetable oils and animal fats and can be used in some cars. Bioethanol is produced from the fermentation of some crops for example corn or sugarcane. |
| CMBR Cosmic microwave background radiation | present in the universe and left over from the big bang, used as evidence to support the big bang. |
| Components | A part of an electrical circuit, for example the bulbs or switch or diode. |
| Compression | A place on a longitudinal wave where the density is the maximum. For example, in sound waves where the air is the least spread out. |
| Condensation | When a vapour turns to a liquid on cooling, heat is given out during this change. |
| Conduction | When heat energy is moved because the vibrating particles in a solid conductor pass it on, metals are the best conductors. |
| Convection | When heat energy is moved because of the movement of more energetic particles in liquids and gases. |
| Diffracted | This word describes the circular bending of waves when they pass through a small gap. |
| Diode | A component, which lets electric current pass through in only one direction. |
| Direct current (D.C.) | An electric current that always flows in the same direction. |
| Doppler effect | This phenomenon is the observed change in wavelength and frequency of waves produced from a moving object. The Doppler effect is observed when an ambulance passes and overtakes you. |
| Efficiency | = useful energy out/total energy in (x100%) Efficiency = useful power out/total power in (x100%) |
| Evaporation | The loss of the most energetic particles from the surface of a liquid, it depends on the surface area of the water, temperature, and humidity and movement of the surrounding air. |
| Frequency | The number of waves per second measured in a unit called hertz (HZ). One hertz means one wave in one second. The symbol is ‘f’. |
| Gamma radiation | A radioactive emission with high penetrating power which can be blocked by concrete or lead, it is also a part of the electromagnetic spectrum. |
| Generator | An important piece of equipment found in power stations. It consists of a magnet inside coils of wire, when made to spin it generates an electrical voltage. |
| Infrared Electromagnetic waves | which are given off by hot bodies or objects. A member of the EMS, which come after microwaves and before visible light waves, used in heating devices, and remote controls for televisions, DVD players etc. |
| Isotopes | This is where an element like carbon, has two types of atom, each with different numbers of neutrons in the nucleus. |
| Kinetic energy | Form of energy possessed by objects, which are in motion. |
| Light energy | Form of energy, which is radiated, and produced by luminous objects, for example the sun or a bulb. |
| Longitudinal | A type of wave where particles move from side to side for example sound. This movement is parallel to the direction in which the energy moves. |
| Microwaves | Member of the EMS, which comes after radio waves and before infrared, wavelength ranges from 1mm to 1m. Used in cooking because they excite and heat water molecules. |
| National grid | The collective name given to the power stations, transformers, pylons and cables which distribute electricity around the country. Newton (N) The unit of force. |
| Pitch | This word describes a property of sound waves, a pitch can be 'high' when the frequency or the tone of a note is high, or 'low' when frequency or tone is low. |
| Radio waves | Member of the EMS with the longest wavelength carries the least energy and is the least harmful, used in communication. |
| Rarefaction | A place on a longitudinal wave where the density is the least. For example, in sound waves where the air is the most spread out. |
| Red shift | This is evidence to support the big bang theory. When we view the light from distant stars it contains more wavelengths from the red end of the spectrum, the furthest and fastest stars have show the biggest red shift. |
| Specific Heat Capacity | This means the amount of heat required to raise the temperature of 1kg of a substance by one degree Celsius, the specific heat capacity of water is 4200 J/kg |
| Transformer | These are devices, which are used to increase (step up) or reduce (step down) the voltage of an A.C. supply, which is fed into them, it makes the transmission more efficient. |
| Ultraviolet | Member of the EMS, which come after infrared waves and before x-rays. They are used in tanning, overexposure can be harmful. |
| Vacuum | A place where there is no matter. |
| Velocity | The speed of an object in a particular direction. |
| Voltage | An electricity term, which describes the amount of energy, carried by the current. |
| Wavelength | The distance (m) between consecutive crests or troughs in a transverse wave. Measure in metre units. |
| X-rays | Member of the EMS, which come after ultraviolet and before gamma waves. They are used in hospital scanning equipment, over exposure can be harmful. |
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