Physics Topic 5 - Generation and Transmission of Electricity

Physics Topic 5 - Generation and Transmission of Electricity

1. Renewable and Non-renewable Resources

   • Renewable Resources
     • Hydroelectricity, Wind Turbines, Tidal Power, Solar Energy, Wave Power and Geothermal Energy are all types of renewable energy.
       • Hydroelectricity is generated by falling water in places where water can be trapped in high reservoirs.
       • Tidal power can generate electricity when turbines in a huge barrage (dam) across a river estuary turn as the tides flow in a out.
         • The difference between Wave and Tidal Power is that wave power can generate electricity when floating electrical generators move up and down.
     • Renewable Resources means that it will not run out.
     • Electricity is a flow of charged particles. The voltage gives a measure of the amount of energy transferred by the charges to an electric component
       • We use electricity for many things, and it all has to be generated using other forms of energy.
     • The Current is the rate of charge flowing.
       • The Voltage is an 'electrical pressure'.
   • Non-renewable Resources
     • Non-renewable Resources means that the resources cannot be replaced once they have been used and they will eventually run out.
       • Nuclear Power stations needs to be carefully decommissioned at the end of its life, so no radioactive materials escape into the environment.
         • Which is very expensive.
     • Coal has an estimated 164 years left before it runs out.
       • Gas has an estimated 67 years left before it runs out.
         • Oil has an estimated 41 years left before it runs out.
           • Uranium has an estimated 265 years left before it runs out.
     • Fossil-fuelled power stations produce waste gases, which can cause problems. For example, Carbon Dioxide emissions contribute to climate change.
       • Gases such as Sulfur Dioxide and Nitrogen Oxides can cause acid rain.
     • Not all fossil fuels cause the same amount of pollution.
       • Natural gas is 'cleaner' than coal because it contains less nitrogen and does not contain sulfur.
       • Natural gas power stations also emit less carbon dioxide than other power stations producing the same amount of electricity.

2. Power

   • Investigating Generators
     • If you move a magnet into a coil of wire, a voltage is included in the wire.
       • If the wire is part of a complete circuit, the voltage will cause a current to flow in the circuit.
     • This process is called electromagnetic induction, and the current is produced is called an induced current.
   • Power Consumption
     • We use a lot of power a day, for example when we have a shower or putting the kettle on.
     • Power is measured in Watts.
     • Power (W) = Current (A) x Voltage (V).

3. Energy

   • Generating Energy
     • If you move a piece of wire in a magnetic field, an electric current will flow in the wire.
       • This process is called Electromagnetic Induction, and a current produced in this way is an Induced Current.
     • Some bikes have dynamo's attached to the wheels and when the wheels spins it turns the dynamo, which produces electricity, which powers the lights.
   • Paying for Electricity
     • The unit of measurement for energy is the 'Joule' (J). The amount of energy that is used by a working appliance each second is known as its power.
       • The unit of measurement for power is joule per second or watt (W). (1W = 1J/s)
         • (1 kW = 1000 W)
     • You can work out the cost of electricity using this formula.
       • cost (p) = power (kilowatt,kW) x time (hour, h) x cost of 1 kWh (p/kWh)
     • Power (watt, W) = energy used (joule, J) ------------------------- time (second, s)
       • P = E ------ T
   • Transmitting Electricity
     • Electricity is sent from power stations to homes, schools and factories by a system of wires and cables called the National Grid.
     • The power comes from the Power Station into a step up transformer (this helps to stops the energy being wasted as heat in the transmission lines).
       • The energy travels through the transmission lines into a step down transformer, so it is ready for the factories.
         • The energy then goes through another step down transformer, so it is ready for houses, shops and offices.
     • Voltage (primary) = Turns (primary) __________________________________ Voltage (secondary) = Turns (secondary)
       • V (p) = N (p) ________________ V (s) = N (s)

4. Reducing Energy

   • There are loads of things you can do to reduce you energy.
     • Solar Panels, Loft Insulation, Double-glazing, Cavity-wall Insulation, Insulation on Hot-wat Tanks and Draughtproofing.
   • The lenght of time it takes you to save the amount of money it costs to buy the item is Payback Time.
     • Payback Time = Cost ------------------ Savings per year