EDEXCEL AS PHYSICS DC ELECTRIC+NATURE OF LIGHT 0.0 / 5 PhysicsDC ELECTRICITY+NATURE OF LIGHTASEdexcel Created by: johnpithersCreated on: 02-06-15 20:55 Describe a semiconductor? Number of free electrons varies with temperature 1 of 27 Describe free electrons? Electrons that arent held around nuclei and can move 2 of 27 Describe a metal in terms of free electrons? High number of free electrons 3 of 27 Define 1 amp? 1 coulomb passes in 1 second 4 of 27 Whats the equation for charge? Q=IT 5 of 27 Describe drift velocity? Velocity of electrons moving towards the positive terminal 6 of 27 What happens to free electrons as they move round a circuit? They lose energy 7 of 27 What is the term for the voltage between 2 points? Potential difference 8 of 27 Define 1 volt? 1 joule transferred when 1 coloumb passes 9 of 27 Whats the equation for electrical energy? E=ITV 10 of 27 What are 2 derived equations for power? p+I^2R and P=v^2/R 11 of 27 What is resistance? Collision during movement of free electrons 12 of 27 What happens to metals at higher temperatures? Atoms vibrate more strongly and have more violent collisions causing more resistance 13 of 27 Define 1 amp? 1A flows when 1V is applied 14 of 27 What material obeys ohms law? Metallic conductor at constant temperature 15 of 27 Whats the formula for resistance and resistivity? R=PL/A 16 of 27 What is resistivity? Resistance between 2 points on a 1m^3 specimen 17 of 27 Whats the relationship between LDR and resistance? high light=low resistance 18 of 27 Whats the relationship between thermistor and resistance? high temp=low resistance 19 of 27 What is emf? Voltage produced by a cell 20 of 27 What is emf alternatively? Maximum pd across terminals 21 of 27 Whats the formula for emf? E=IR+Ir 22 of 27 What is quantum light theory? Light sometimes behaves like waves and sometimes like particles 23 of 27 What is work function? Energy required to just release a photoelectron 24 of 27 Whats the formula for kinetic energy? energy-work function 25 of 27 whats the formula for electron volts? EV=1.6x10^-19J 26 of 27 Whats the formula for efficiency? Useful/total 27 of 27

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