• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month
Page
1. 1
1
2. 2
2

# Making electricity.

Extracts from this document...

Introduction

## Making electricity

You can make an electric current in a wire if a wire is at right angles to a magnetic field and the magnetic field is changing. We say that the electric current has been induced.

You can change the magnetism by moving the wire past the magnet, or moving the magnet past the wire. It will show up better on a meter if you use a coil of wire.

A current is generated only when the magnet is moving.

The current stops if the magnet stops moving - even if it is inside the coil.

The current goes the other way if the magnet moves in the opposite direction

Middle

If you keep the magnet still and move the wire, you induce a current in exactly the same way.

## Generators

Generators induce a current by moving a magnet inside a coil of wire, or by moving a coil of wire inside a magnetic field. One example of a generator is a bicycle dynamo.

Bicycles sometimes have dynamos which rub against the back tyre. As the bike moves, a wheel on the top of the dynamo turns a magnet inside a coil.

### Generators from motors

Simple electric motors generate electric currents when you spin them. Instead of using electric current to turn a coil, turning the coil produces an electric current.

## Transformers

Conclusion

Voltage across coil 1/voltage across coil 2 = number of turns in coil 1/number of turns in coil 2

### Transformers in real life

Transformers are not 100% efficient. As the current flows through the coils some heat will be produced. The output of a real transformer will be less than predicted by this calculation, so sometimes you will be asked for the percentage efficiency of a transformer.

## The National Grid

Electricity is carried around the country by the National Grid. There is less energy loss at high voltages, so the electricity is sent through the wires at 275kV and 400kV. Power stations usually work at 25kV, so they use transformers to increase the voltage. Transformers are also used at the other end to bring the voltage down to 240V.

This student written piece of work is one of many that can be found in our AS and A Level Fields & Forces section.

## Found what you're looking for?

• Start learning 29% faster today
• 150,000+ documents available
• Just £6.99 a month

Not the one? Search for your essay title...
• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Related AS and A Level Fields & Forces essays

1. ## Investigating the forces acting on a trolley on a ramp

5 star(s)

However, at larger values of O, which occur when the ramp is steeper, the value of sin O - � cos O becomes larger; sin 10.8 - � cos O = 0.18738 - (0.029679 x cos 10.8) = 0.15823 (5d.p.)

2. ## To see how the number of coils on an electromagnet affect its strength.

The results that were recorded did indeed show a pattern. As the number of coils gradually increased so did the number of paper clips that were attracted. For example, when the coils were turned 20 times, the number of paper clips that were picked was a total of 19.

1. ## What Affects the Strength of Magnetism Exerted By an Electromagnet?

This will inflict the alignment of domains on the 'Soft-Iron Core'. Consequently, the Soft-Iron Core will become a stronger magnet with a larger magnetic field. This field will be capable of inflicting its magnetism (alignment of domains) on Cobalt, Nickel or Iron in range.

2. ## Induction motors

With the three-phase current flowing through the coils a rotating magnetic field is produced, the field then induces a current in the conductors on the shaft. This is where three-phase power outperforms single phase. For the shaft to rotate smoothly without stopping the three coils situated at 120� from each other are supplied with power at precise intervals.

1. ## Investigating a factor affecting the voltage output of a transformer.

primary and secondary coils Increasing the distance leads to the attenuation of magnetic field lines, decreasing secondary voltage * Material of wire Different metal wires have different resistances; increasing the resistance of the coil's wire decreases the current, decreasing rate at which the magnetic field lines alternate, so less magnetic

2. ## EMF Investigation - electricity and magnetic fields.

has to neglected until the actual experiment itself, then it could be properly recorded and presented. As a criterion, the other factors have to be kept constant in order to make this a fair test. Here are the variations: 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100

1. ## Electromagnetism through a coil.

The magnetism of the material is due to the movement of electrons in the atoms of the domain. In an Unmagnetized sample of material, the domains point in random directions, or form closed loops, so that there is no overall magnetisation of the sample.

2. ## Investigation on Transformers.

* Separation of the wire- This variable will be kept constant as well. The secondary coil will be turned on top of the primary coil. Equipment required for the experiment * 2x Voltmeter * Iron Rod * Crocodile Clips * Power pack * Coil * Insulation Tape Method In this

• Over 160,000 pieces
of student written work
• Annotated by
experienced teachers
• Ideas and feedback to