Electricity And Magnetism

Question 1

A material which easily allows an electric current is

Answer 1

an electrical conductor

Question 2

A material which does not allow an electric current is

Answer 2

an electrical insulator

Question 3

Name some good electrical conductors

Answer 3

Any metal (some are better than others!), graphite (a form of carbon), salt water

Question 4

Name some good electrical insulators

Answer 4

Wood, plastic (most non-metals in fact)

Question 5

What instrument is used to measure current?

Answer 5

Ammeter

Question 6

What does an ammeter measure?

Answer 6

Current

Question 7

What is the unit of current and what is its symbol?

Answer 7

Amperes, A

Question 8

If I increase the number of cells in my battery the current will…?

Answer 8

Increase

Question 9

When the charge moves through the cell it gains…?

Answer 9

energy

Question 10

Energy per unit charge is also known as….

Answer 10

potential

Question 11

What is the unit of potential?

Answer 11

volt, V

Question 12

If I connect more bulbs in series with each other the resistance will…and the current will….

Question 13

resistance will increase and the current will decrease

Question 14

What is the unit of resistance

Answer 14

ohm, Ω

Question 15

What is current?

Answer 15

The amount of charge passing a point each second

Question 16

At a junction in a circuit what is the important rule to remember?

Answer 16

total current in = total current out

Question 17

Which poles of a magnet attract each other?

Answer 17

The opposite poles (North and South)

Question 18

What happens when like poles of magnets come together

Answer 18

They repel

Question 19

Give some examples of magnetic materials

Answer 19

Iron, Steel, Cobalt, Nickel

Question 20

Give some examples of non-magnetic materials

Answer 20

Plastic, Wood, Paper, Rubber, Glass

Question 21

Why does the Earth have a magnetic field

Answer 21

The core of the earth is a rotating ball of Iron

Question 22

What is a magnetic field?

Answer 22

The region around a magnet where other magnetic materials experience a force

Question 23

How are magnetic fields represented in diagrams?

Answer 23

Magnetic field lines

Question 24

How could you visualise the field around a magnet?

Answer 24

Iron filings, or using a compass

Question 25

Draw the magnetic field around the Earth

Answer 25

Remember - the Earth's geographic north pole is a magnetic south pole (we still call it magnetic north when referring to where our compass needle points!)

Question 26

What is the shape of a magnetic field around a wire and how can we tell the direction of the field lines?

Question 27

Circular. Right hand "thumbs up" rule. Thumb points in the direction of the current, the fingers curl in the direction of the field

Question 28

When a current flows in a wire a magnetic field is generated. What do we call this effect?

Answer 28

Electromagnetism

Question 29

Name 3 ways to increase the strength of the magnetic field around a solenoid

Answer 29

* Increase the current * Increase the number of turns on the coil * Add an iron core

Question 30

What is one of the major advantages of an electromagnet compared to a permanent magnet

Answer 30

Electromagnets can be switched on and off

Question 31

What is a relay circuit used for?

Answer 31

To activate high voltage circuits using low voltage circuits (this protects the user from high currents)

Question 32

List some uses of electromagnets

Answer 32

In relays (e.g. to switch of floodlights or x-ray machines in hospitals), in scrapyards to move parts, maglev trains, in electric motors, in rollercoaster braking