| A | B |
|---|
| Charge | Property that causes attraction or repulsion |
| Coulomb | Unit of charge |
| electron | Smallest negative charge - Q = 1.6x10-19C |
| conductor | Material that charges can move freely in |
| insulator | Material that doesn't allow a current - has not free charges |
| electroscope | Device for measuring chatge e.g. gold leaf electroscope |
| earth | Point of zero potential - a place that can absorb or release charge without changing its charge |
| coulomb's law | F = kqq/r^2 |
| electric field | Area where a charge can have an effect on other charges. Force acting on a unit positive charge |
| field line | Line that shows direction of electric field - closer field lines mean stronger field |
| potential difference | Ammount of energy a charge gains or loses moving between 2 points |
| volts | Unit of p.d. - Joules per coulomb |
| electronvolt | Unit of energy - the energy given to an electron accelerated across 1 volt - used for measuring atomic sized amounts of energy |
| metallic conduction | Conduction by free conduction electrons moving through a lattice of positive ions |
| current | Flow of charges - measured in amperes |
| resistance | Voltage required to drive a unit current - ratio of voltage and current |
| ohm's law | Voltage is proportional to current UNLESS temperature changes |
| ohmic | Follows ohm's law - gives straight line V-I graphs |
| power dissipation | Rate of energy transferred by a current in a resistor |
| diode | Device that allows current to pass in one direction only |
| filament | Resistance wire in a light bulb |
| drift velocity | Speed that electrons move in a wire - very much lower than the speed energy is transmitted |
| series | one after the other |
| parallel | alongside |
| ammeter | Device for measuring current |
| voltmeter | Device for measuring voltage |
| electromotive force | Energy per unit charge given to charges in a cell or a generator |
| internal resistance | Property of a cell where energy is lost as current passes through it |
| magnetic field line | Line showing froce on a free north pole |
| pole | end of a magnet |
| right hand grip rule | relates filed lines and current in coils and solenoids |
| solenoid | Coil of wire |
| straight wire | Produces concentric cylinders of field |
| motor effect | Current perpendicular to a magnetic field produces a force |
| left hand rule | For determining the diretction of force given by the motor effect |
| motor | Device for converting electrical energy into kinetic energy using the motor effect |
| moving charges | are effected by a magnetic field - e.g. an electron beam |
| parallel wires | Give a force between them due to the current. Give the definiton of an ampere. |
| definition of ampere | Current in parallel wires 1 metre apart that givesa force of 4pix10-7N |
| B | Magnetic field strength - Teslas |
