Producing and Distributing Electricity
- National Grid - network of pylons and cables that covers the country
- electricity taken from power stations to homes/industries
- aim of power stations - convert a form of energy into electricty
- a power station has 3 steps;
- 1. generate steam
- 2. pass steam through turbines, making them turn
- 3. movement allows generator to turn it into electricity
- power stations are innefficient, as energy is lost through sound and heat
- fossil fuels: advantages - a concentrated source of energy. Disadvantages - causes acid rain and greenhouse gases, it's expensive to get from countries abroad, and it's unrenewable.
- biomass: advantages - renewable, carbon neutral process, doesn't require imports of material. Disadvantages - takes time (and space) to grow, you need a lot of material to get enough energy.
- nuclear power: advantages - quick, effective. Disadvantages - potentially dangerous.
- photocells: advantages - renewable, sturdy, wireless, low maintenance. Disadvantages - doesn't work at night, energy reduced in bad weather.
- wind power: advantages - cheap, renewable. Disadvantages - requires wind, looks ugly.
1 of 4
The Dynamo Effect
- electromagnetic induction; creating a voltage, and sometimes current, in a wire experiencing a change in magnetic field.
- dynamo effect; using electromagnetic induction to turn kinetic energy into electricity.
- electromagnetic induction happens when;
- electrical conductor moves through magnetic field
- OR magnetic field moves through electrical conductor
- to reverse voltage or current, you need to reverse the direction of movement
- increasing the strength of magnet, the number of turns on the coil or the speed of movement will make a bigger voltage and current
- generators move coil in magnetic field, and every half turn the current swaps direction
- generators produce AC
- dynamos on bikes rotate magnet near coil
2 of 4
Supplying Electricty Effectively
- to transmit lots of electricity, high voltage/current in needed, but this means more heat energy wasted through cable.
- cheaper to increase voltage while keeping current low, as less energy wasted through cable heat.
- step-up transmformers increase voltage
- step-down transformers make it safe to be used in homes
- transformers only work on alternating current (AC)
- power stations aren't efficient.
- total energy input = useful energy output + waste energy output
- efficiency = useful energy output / total energy input
3 of 4
- power measured in watts (W) or kilowatts (kW)
- 1 watt = 1 joule per second
- to work out power of appliance: Power (W) = Voltage (V) x Current (A)
- kilowatt-hour (kWh) is amount of energy converted by 1kW appliance
- energy supplied (kWh) = power (kW) x time (h)
- cost = number of units x price per unit
- off-peak electricity is electricity supplied at night
- advantages of off-peak electricity:
- cost-effective for company
- cheaper for consumers
- disadvantages of off-peak electricity:
- risk of fire in homes
- stop enjoying use of electricity in day
4 of 4