A-Level Physics OCR A Definitions

acceleration - answer-Rate of change of velocity. Vector quantity Acceleration of free fall - answer-Rate of change of velocity of object falling in a gravitational field air resistance - answer-Drag/resistive force experienced by objects moving through air Ammeter - answer-Device used to measure electric current-placed in series (ideally 0 resistance) ampère - answer-Base SI unit of electric current, A, current flowing in two parallel wires in a vacuum 1m apart such that atractive force 2.0*10-7 per metre length of wire between them amplitude - answer-Max displacement from equlibrium point of a particle in a wave angle of incidence - answer-Angle between direction of travel of incident ray and normal angle of reflection - answer-angle between direction of travel of reflected ray and normal anion - answer-negatively charged ion -attracted to anode antiparallel - answer-Same line but opposite directions antiphase - answer-Particles ocillating where one reaches max displ. whilst other reaches min displ. Archimedes' Principle - answer-Upthrust on a object in fluid equals weight of fluid it displaces average speed - answer-Rate of change of distance in time average velocity - answer-rate of change of displacement in time base unit - answer-one of 7 units that form building blocks of SI measurements battery - answer-collection of cells that transfer chemical energy to electrical energy braking distance - answer-distance travelled by vehicle from time brakes applied to full stop