Electricity And Magnetism

Question 1

What is an electrical conductor?

Answer 1

A material which easily allows an electric current.

Question 2

What is an electrical insulator?

Answer 2

A material which does not allow an electric current.

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, what will happen to the current?

Answer 8

The current will increase.

Question 9

When the charge moves through the cell, what does it gain?

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, what happens to the resistance and current?

Answer 12

Resistance will increase and the current will decrease.

Question 13

What is the unit of resistance?

Answer 13

Ohm, Ω.

Question 14

What is current?

Answer 14

The amount of charge passing a point each second.

Question 15

What is the important rule to remember at a junction in a circuit?

Answer 15

Total current in = total current out.

Question 16

Which poles of a magnet attract each other?

Answer 16

The opposite poles (North and South).

Question 17

What happens when like poles of magnets come together?

Answer 17

They repel.

Question 18

Give some examples of magnetic materials.

Answer 18

Iron, Steel, Cobalt, Nickel.

Question 19

Give some examples of non-magnetic materials.

Answer 19

Plastic, Wood, Paper, Rubber, Glass.

Question 20

Why does the Earth have a magnetic field?

Answer 20

The core of the earth is a rotating ball of Iron.

Question 21

What is a magnetic field?

Answer 21

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

Question 22

How are magnetic fields represented in diagrams?

Answer 22

Magnetic field lines.

Question 23

How could you visualize the field around a magnet?

Answer 23

Iron filings, or using a compass.

Question 24

What is the shape of a magnetic field around a wire?

Answer 24

Circular.

Question 25

How can we tell the direction of the magnetic field lines around a wire?

Answer 25

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

Question 26

What do we call the effect when a current flows in a wire and generates a magnetic field?

Answer 26

Electromagnetism.

Question 27

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

Answer 27

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

Question 28

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

Answer 28

Electromagnets can be switched on and off.

Question 29

What is a relay circuit used for?

Answer 29

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

Question 30

List some uses of electromagnets.

Answer 30

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