Electricity

Static Is stationary E.g. Brush your hair Wool socks in tumble drier Current Flows around circuit E.g. turn on light Walkman Electricity occurs in 2 different forms

Static Electricity Occurs with materials which are insulators Rubbing adds or removes electrons Object becomes charged Like objects repel, unlike attract

Current Electricity Electrons flow through a conductor Negative to positive Circuit = continuous loop for electrons to flow Needs energy supply Energy user

Electrical components Wire Ammeter Battery Fuse Connected wires Bulb Switch Voltmeter diode Resistor Rheostat

CIRCUIT TYPES The simplest type of circuit involves electricity going around with no “choices” (electrons don’t really choose). This is called a Series circuit. Draw the path the electrons travel. The other main type of circuit has two or more branches. This is called a Parallel circuit. Draw on the electron flow. What sort of circuit is this? A parallel… but, more importantly… A short circuit.

Series circuit Has a single loop for electrons to travel round Components are connected one after another Current has to travel through all components Current is the same at all points Voltage is shared between components

Parallel circuit Has two or more paths for electrons to flow down Current is shared between the branches Sum of the current in each branch = total current Voltage loss is the same across all components

Electricity Electricity is forced around a circuit by an electrical force field Flow of electricity around a circuit is called CURRENT (I) Current measured in amps (A) Voltage (V) – Increase or decrease in the amount of electrical energy carried by the current.

Current (I) Current is the flow of electrons around a circuit DC = direct current like battery Electrons flow in one direction AC = Alternating current like mains Electron flow changes direction 50x per second

Ammeter Measures CURRENT(I) Unit = Amp (A) Current is flow of electrons Connect in series at the point you wish to measure RED to RED and BLACK to BLACK

3 pin plug 3 wires P = phase (brown or red) N = neutral (blue or black) E = earth (yellow/green or green)

Voltage (V) Gain or loss of energy as it passes through a component Voltage lost = voltage gained In series voltage loss is shared between components In parallel voltage loss is the same across all components

Voltmeter Measures voltage Unit = Volt (V) Voltage increases as it passes through energy suppliers Voltage is decreased as it passes through users Connect in parallel around a component

SUMMARY In SeriesIn Parallel Current Voltage Always the same The branches share electrons and add to the total Voltage from source = voltage used Voltage is shared between power users Voltage is the same in all branches

Electricity Generation

Fossil Fuels

Hydro Dam

Hydroelectric power

Nuclear power

Wind Power

Tidal Power

Geothermal

Solar Solar water heating Photovoltaic cells Solar furnace

Resistance (R) The amount that a component slows the current As the electrons are slowed by a resistor, energy is lost in the form of heat. This means that current, resistance and voltage must be linked. This is Ohms law The unit of resistance is the ohm, symbol  V IR×

Power Energy used by component per second Unit of power is the Watt, symbol is W One watt means that 1 joule of electrical energy is being used up per second. Current, voltage and power are linked P IV×

PROBLEMS 1. Fill in the gaps in the table. ab cd ef g h i j kl

Temperature & Heat Temperature is a measure of the average kinetic energy of the particles. Degrees Celsius ( C ) Heat energy is a measure of the total kinetic energy of all the particles making up an object. joules ( J ) or kilojoules

Effects of Heating Temperature Rise Expansion Change of State

Transferring Heat Energy Conduction Convection Radiation TRAVEL

Diodes and Switches Diodes let electrons flow in one direction Switches allow electrons to flow or not