Presentation on theme: "Generating Electricity"— Presentation transcript:
1 Generating Electricity To generate a voltage (electricity) you need:a magnetic fielda conductormovementVThe size of the voltage induced depends on:strength of the magnets (magnetic field)the length of coiled wire (conductor)speed of movement
3 The DynamocoilAs the dynamo is turned, the magnet rotates beside the coil of wire.An A.C voltage is generated in the coilsPower station generators are much bigger and use electromagnets.electrical outputrotating magnet
10 InfoSpeaking of R2-D2, this M.A.R.S. Floating Wind Generator looks a lot like a flying R2 droid on its side. This helium-filled, horizontal-rotating M.A.R.S. (Magenn Power Air Rotor System) will go into production with its 4.0 kw unit this year with 7 more models planned for release in the next 4 years. The 2010 and 2011 planned models will be able to power a small town on their own.The generated electrical energy travels town its 1000-foot tether rope, with the energy available for immediate use. With its helium, balloon-like flying system, M.A.R.S. can fly higher than other wind turbines, able to reach altitudes with much higher wind speeds.
12 greater amplitude (bigger voltage) higher frequency (faster rotation) Resultsslow speedhigh speedgreater amplitude (bigger voltage)higher frequency (faster rotation)
13 transformers require an AC voltage A transformer consists of 2 coils of wire and iron core which passes through both coils.iron coreprimary coilsecondary coiltransformers require an AC voltage
14 secondary voltage (VS) The circuit symbol for a transformer is:An AC voltage in the primary coil induces (creates) a voltage in the secondary coil.The size of the secondary voltage depends on:size of primary voltagenumber of turns on each coil.NPVPVSNSQuantityUnitsecondary voltage (VS)primary voltage (VP)secondary turns (NS)primary turns (NP)volts (V)** NO UNIT **
15 This is a STEP DOWN transformer Example 1Calculate the secondary voltage for the transformer shown.1000 T230 VACVS52 TThis is a STEP DOWN transformer
16 This is a STEP UP transformer Example 2Calculate the secondary voltage for the transformer shown.300 T50 VACVS12,000 TThis is a STEP UP transformer
25 step-down transformer Power LinesElectricity is provided by power lines called The National Grid.400,000 V230 V25,000 Vstep-up transformerstep-down transformerThe output voltage is stepped up to reduce power loss in the wires of the national grid.
26 Stepping up the voltage reduces the size of the current. Smaller current, less power loss.Example 1A transmission power line of length 60km has a resistance of 2 Ω per kilometre. The total current in the cable is 50 A.Calculate the power loss in the transmission line.