P2b

Question 1

How is electricity generated using the dynamo effect?

Answer 1

Move the wire or the magnet.
Using electromagnetic induction to transform kinetic energy into electrical energy is called the dynamo effect.
There are two different situations where you get EM induction:
An electrical conductor (coil/wire) moves through a magnetic field.
Magnetic field through an electrical conductor changes (gets bigger/smaller/reverses).

Question 2

What type of current does a generator produce?

Answer 2

Alternate current.

Question 3

What type of current does a battery produce?

Answer 3

Direct current.

Question 4

What are the ways that dynamo can be increased to get a bigger voltage or current?

Answer 4

Increase:
The strength of the magnet.
The number of turns on the coil.
The speed of the movement.

Question 5

What do voltage time graphs show?

Answer 5

Current reverses direction regularly.

Turning the coil faster produces not only more peaks but a higher voltage and current too.

Question 6

What are the main stages in the production and distribution in electricity?

Answer 6

The aim of a power station is to convert one kind of energy (e.g. the energy stored in fossil fuels) into electricity.
The power station produces electricity.
The National Grid connects power stations to consumers. The National Grid is the network of pylons and cables which covers the whole country. It takes electricity from power stations to consumers which are homes, factories, offices and farms.

Question 7

How do simple AC generators work?

Answer 7

Generators rotate a coil in a magnetic field. Every half a turn, the current in the coil swaps direction because one part of the coil sometimes heads for the magnet’s north pole and sometimes for the south.

Question 8

How is electricity generated at a conventional power station?

Answer 8

The fuel is used to produce heat which then generates steam - this is the job of the boiler. The moving steam drives the blades of a turbine. This rotating movement from the turbine is converted to electricity by the generator using electromagnetic induction.

Question 9

What is a disadvantage of conventional power stations?

Answer 9

There is a significant waste of energy.

Question 10

What is the equation for total energy input for fuel in a power station?

Answer 10

total energy input = useful energy output + waste energy output

Question 11

What is the equation for efficiency for power stations?

Answer 11

efficiency = useful energy output/total energy input (x100)