P2b - Power stations 1

P2b - Power stations 1

What’s in P2b?

• How to turn kinetic energy into electrical energy

• What alternating current (AC) is

• How power stations work

• How to calculate power station efficiency

• How electrical energy is distributed by the national grid

Kinetic energy electrical energy

Dynamo effect:

• You can generate electricity by moving a __________ past a coil of wire or vice versa

• This is called the __________ effect

Dynamo effectThe voltage produced can be increased in

4 ways:

1.

2.

3.

4.

Generators

Generators

• Use __________ effect to generate electricity

• Contain electromagnets, which consist of coils of wire wrapped around ________ cores

Alternating current (AC)

Direct current (DC)

Inside a power station

Inside a power station

Inside a power station

Power station energy transfers

1. Start -

2.

3.

4. Finish -

Power station efficiencyThe efficiency of a power station can be

calculated using this equation:

Try these efficiency questions:

How efficient are the following power stations:

1. 60 J wasted for every 40 J of electricity?

2. 200 J electricity from every 500 J fuel?

3. 500 J from every kJ of fuel?

4. 100 J heat energy wasted per 2 kJ of

electricity produced?

The national grid

• The national grid is a transmission network that transfers electricity from power stations to our homes

• Power stations produce electricity at a relatively low voltage

• Transmission wires carry high voltage (100 000 V +)• The mains voltage that we use is 230 V• Devices called transformers are used to change the

voltage

National grid diagram