Year 8 electricity (physics)

• Electricity is the presence or flow of charged particles
• An electric current is the flow of electrons around a circuit
• a current never runs out
• there is a cell which pushes the charge around the system
• the charge everywhere starts to move at the same time
• When an insulator is used in the circuit the electrons can’t travel around the circuit
• when a conductor is used in a circuit the electrons can travel through easily
• conductors are materials which allow electrical current to flow through them easily
• metals are generally good electrical conductors
• insulators are materials which are poor conductors and do not allow electrical current to flow through them easily
• zinc, copper and iron are good conductors
• steel, silver, gold and sea water are all good conductors
• diamond, glass and rubber are all good insulators
• an ammeter is an instrument for measuring electric current in amperes
• a voltmeter measures the potential difference between two points in volts
• Series circuits have one loop or pathway
• parallel circuits have two or more loops
• there are always electrons in the metal
• the current is the amount of charge flowing per second
• when the circuit is complete, charged particles (electrons) move in the metal wires
• electrons are negatively charged so they move from the negative to positive terminal of battery
• the current has the same value everywhere in a series circuit
• adding more components to a series circuit increases the total resistance in the circuit, so less current flows and the bulbs appear dimmer
• in a parallel circuit the total current through the battery is the sum of the current through separate branches
• if you add another branch to a parallel circuit, the current in the other branches stays the same, however the total current increases
• A1=A2+A3 (formula for current in parallel circuit)
• adding more components to a parallel circuit causes more current to flow through the cell, not less
• Current is measured in amps
• potential difference is measured in volts
• Resistance is measured in ohms
• current is the measure of the rate of flow of the electrons within the circuit. Not how fast the electrons travel.
• current is constant and the same at every point in a single loop/branch of a circuit
• inside of a wire are metal atoms
• potential difference is a measure of the difference in electric potential energy between two points in a circuit
• a voltmeter measure the difference between the higher electrical energy and the lower electrical energy
• the potential difference across the power supply must equal the potential difference across the components in that loop
• resistance is a measure of how difficult it is for current to flow
• Resistance is measured in ohms
• resistance = voltage / current
• static electricity builds up when two insulators rub against each other