Electricity and Magnetism

Question 1

What is an electrical conductor?

Answer 1

An electrical conductor is a material that allows the flow of electric current.

Question 2

What is an electrical insulator?

Answer 2

An electrical insulator is a material that does not allow the flow of electric current.

Question 3

Name some good electrical conductors.

Answer 3

Some good electrical conductors include metals (some are better than others), graphite (a form of carbon), and salt water.

Question 4

Name some good electrical insulators.

Answer 4

Some good electrical insulators include wood and plastic (most non-metals).

Question 5

Draw the circuit symbol for a cell.

Answer 5

A cell is represented by a long line and a short line.

Question 6

Draw the circuit symbol for a battery.

Answer 6

A battery is represented by two or more cells connected together.

Question 7

Draw the circuit symbol for a bulb.

Answer 7

A bulb is represented by a circle with a cross inside.

Question 8

Draw the circuit symbol for a switch.

Answer 8

A switch is represented by a break in a line with a small lever.

Question 9

Draw the circuit symbol for a variable resistor.

Answer 9

A variable resistor is represented by a zigzag line.

Question 10

Draw the circuit symbol for an ammeter.

Answer 10

An ammeter is represented by a circle with an ‘A’ inside.

Question 11

What instrument is used to measure current?

Answer 11

An ammeter is used to measure current.

Question 12

What does an ammeter measure?

Answer 12

An ammeter measures the amount of current flowing through a circuit.

Question 13

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

Answer 13

The unit of current is amperes, symbolized as ‘A’.

Question 14

What happens when I increase the number of cells in my battery?

Answer 14

The current will increase.

Question 15

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

Answer 15

It gains energy.

Question 16

Energy per unit charge is also known as?

Answer 16

Energy per unit charge is known as potential.

Question 17

What is the unit of potential?

Answer 17

The unit of potential is the volt, symbolized as ‘V’.

Question 18

If I connect more bulbs in series, what happens to the resistance and current?

Answer 18

The resistance will increase and the current will decrease.

Question 19

What is the unit of resistance?

Answer 19

The unit of resistance is the ohm, symbolized as ‘Ω’.

Question 20

What is current?

Answer 20

Current is the amount of charge passing a point each second.

Question 21

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

Answer 21

The total current in must equal the total current out.

Question 22

Which poles of a magnet attract each other?

Answer 22

The opposite poles (North and South) attract each other.

Question 23

What happens when like poles of magnets come together?

Answer 23

They repel each other.

Question 24

Give some examples of magnetic materials.

Answer 24

Examples of magnetic materials include iron, steel, cobalt, and nickel.

Question 25

Give some examples of non-magnetic materials.

Answer 25

Examples of non-magnetic materials include plastic, wood, paper, rubber, and glass.

Question 26

Why does the Earth have a magnetic field?

Answer 26

The core of the Earth is a rotating ball of iron.

Question 27

What is a magnetic field?

Answer 27

A magnetic field is the region around a magnet where other magnetic materials experience a force.

Question 28

How are magnetic fields represented in diagrams?

Answer 28

Magnetic fields are represented by magnetic field lines.

Question 29

How could you visualize the field around a magnet?

Answer 29

You can visualize the field using iron filings or a compass.

Question 30

Draw the magnetic field around a bar magnet.

Answer 30

The magnetic field around a bar magnet is represented by lines emanating from the poles.

Question 31

Draw the magnetic field around the Earth.

Answer 31

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 32

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

Answer 32

The shape is circular. The right-hand 'thumbs up' rule is used: thumb points in the direction of the current, fingers curl in the direction of the field.

Question 33

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

Answer 33

This effect is called electromagnetism.

Question 34

Draw the magnetic field around a coil/solenoid.

Answer 34

The magnetic field around a solenoid is represented by concentric circles.

Question 35

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

Answer 35

1. Increase the current. 2. Increase the number of turns on the coil. 3. Add an iron core.

Question 36

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

Answer 36

Electromagnets can be switched on and off.

Question 37

What is a relay circuit used for?

Answer 37

A relay circuit is used to activate high voltage circuits using low voltage circuits, protecting the user from high currents.

Question 38

List some uses of electromagnets.

Answer 38

Electromagnets are used in relays, scrapyards to move parts, maglev trains, and electric motors.