Electricity And Magnetisms

Question 1

Magnetic fields

Answer 1

A region in which a magnetic pole experiences a force

Magnetic field lines are loops
Then field lines come out of the North Pole and go to into the south
The pole are the strongest around a magnet where the lines are the closest

Rules
- N and S attract
(Opposite attract)
-N and N poles repel
Each pole is attracted to a magnetic material

Question 2

Magnetic materials

Answer 2

A magnetic material experiences a force when place in a magnetic field
Eg:
- iron
- steel
- nickel etc

Magnetically soft materials (iron)
- are easy to magnetise
-easily lose their magnetism

Magnetically hard materials (steel)
- are hard to magnetise
- Do not easily lose their magnetism

Ferrous metals/materials - contain iron

Question 3

Permanent magnets vs electromagnets

Answer 3

Permanent - Are made of magnetically hard materials as we dont want them to lose magnetism

Electromagnets - are made out of magnetically soft materials, as we want them to be able to easily gain and lose their magnetism

Question 4

Induced magnetism

Answer 4

When a magnetic material is placed in a magnetic field, the material can temporarily become magnetised

This means that the magnetic material will have its own magnetic field and its own poles and can attract other materials

They can be stroked by a magnet or hammered in a magnetic field or putting them inside a coil with direct current, to magnetise them

They can be demagnetised by hammering them heating them or putting them inside a coil with alternating current through it

Question 5

Uses of electromagnets and permanent magnets

Answer 5

Electromagnets
- Loud speakers
- Electromagnetic bells
- Relay switches
- Circuit breakers

Question 6

Positive and negative charges

Answer 6

Objects can be given one of two types of electric charge

• positive
• negative

(Remember opposites attract so negative and positive charges are attracted)

Electrical charges is measured in a unit called coulombs

Electrical charges have field patterns (negative charges have field lines going inwards towards them)
(Positive charges have field going outwards)

Question 7

Electrons and conductions in terms of electrons

Answer 7

Charging a body involves the addition of removal of electrons

Removal = negative charge
Addition = positive charge

Conductor is a material that allows charge/electrons to flow through it
An insulator is a material that does not allow the flow of charge /electrons through it

Question 8

Charging by Induction

Answer 8

Electrons in the aluminium foil are attracted to the positively charged rod
This causes the top of the foil to become negatively charged, whilst the bottom edge of it will be left with a positive charge
The attraction between the positive rod and the negative charges on the top surface of the foil will cause the foil to be attracted to the rod