AQA a level physics paper 2

Line of force - answer-Direction a hypothetical "free north pole" would travel in the field. Otherwise known as a field line. Motor effect - answer-Effect in which a current in a magnetic field experiences a force. Fleming's left hand rule - answer-Way of working out the directions involved in the motor effect. Magnetic flux density - answer-Force per unit length per unit current on a conductor perpendicular to the field lines. Often referred to as the strength of the magnetic field. Couple - answer-Pair of forces in opposite directions that try to turn an object. Acts on the coil of a motor. Thermionic - answer-Property of a material that means that when it gets hot, it emits electrons. Cyclotron - answer-Spiral particle accelerator. Frequency - answer-Number of rotations per second, given by 1/T. Mass spectrometer - answer-Device that separates a constituents of a substance by their masses. Ion - answer-Charged atom. Velocity selector - answer-Component that uses an opposing electric and magnetic field to ensure all particles going straight through have the same speed and direction. Vacuum - answer-Space where (nearly) all particles have been removed (evacuated). Electromotive force - answer-Force on electrons that tries to push them along. Known as the emf. Electromagnetic induction - answer-Phenomenon in which a changing magnetic field, relative to a wire, will produce an emf. Fleming's right hand rule - answer-Also known as the dynamo rule. Works out directions involved in electromagnetic induction. Solenoid - answer-Electrical coil. Lenz's law - answer-"The direction of the induced current is always such as to oppose the change that caused the current". Magnetic flux - answer-Product of the magnetic flux density and the area. Magnetic flux linkage - answer-Product of the magnetic flux and the number of turns of the coil. Faraday's law - answer-"The induced emf in a circuit is equal to the rate of change of flux linkage through the circuit". Alternator - answer-Generator of AC. Back emf - answer-An emf generated in a motor that works against the current that is powering the motor. Step-up - answer-Transformer that raises the voltage and lowers the current (answer is hyphenated!) Step-down - answer-Transformer that lowers the voltage and raises the current (answer is hyphenated!) National Grid - answer-Network of transformers and cables that transmits power across the country. Pressure - answer-The force per unit area exerted normally (at 90 degrees) on a surface. Boyle's law - answer-For a fixed mass of gas at constant temperature, pV = constant. Charles' law - answer-For a fixed mass of gas at constant pressure, V/T = constant. Pressure law - answer-For a fixed mass of gas at constant volume, p/T = constant. Brownian motion - answer-The random and unpredictable motion of a particle (like a smoke particle) caused by molecules of the surrounding material colliding with it at random. Avagadro constant - answer-Number of particles in a mole of a substance. 6.02x10^23. Mole - answer-Amount of substance with 6.02x10^23 particles in it. Molarity - answer-Number of moles in a substance. Measured in mol. Molar mass - answer-Mass of 1 mol of a substance.