Electromagnitism

Question 1

What is an example of a ferromagnetic material?

Answer 1

Iron, nickle, cobalt

Question 2

What is magnetism?

Answer 2

Magnetism is a force that can attract or repel objects and is created by moving electric charges.

Question 3

What exists in the space surrounding a magnet?

Answer 3

A magnetic field

A magnetic field can exert forces on magnetic materials like iron, nickel, and cobalt.

Question 4

What happens when a magnetic material enters a magnetic field?

Answer 4

• Experiences a force
• Can be either attraction (pull) or repulsion (push)

The force is stronger closer to the magnet.

Question 5

How can the shape of a magnetic field be made visible?

Answer 5

By sprinkling iron filings around the magnet

This visualizes the field lines and their direction.

Question 6

Who discovered that electricity could cause magnetism?

Answer 6

Hans Christian Øersted

He observed that a wire carrying an electric current caused a compass to move.

Question 7

What does a single current-carrying wire create in a magnetic field create?

Answer 7

It creates a circular magnetic field that gets weaker as the distance from the wire increases.

Question 8

What does the Right-hand grip rule help measure?

Answer 8

The rule is used to determine the direction of the magnetic field around an electrical wire.

This rule helps visualize the direction of the field based on current flow.

Question 9

What is a solenoid?

Answer 9

A coil of loops of wire that creates a stronger, straighter magnetic field similar to that of a bar magnet.

Question 10

What can be added inside a solenoid to create a stronger magnetic field?

Answer 10

A soft iron core

Pure iron is easily magnetized and enhances the magnetic effect when current is applied.

Question 11

What is an electromagnet?

Answer 11

A type of magnet that can be turned on and off. Its a type of temporary magnet.

It uses electric current to create a magnetic field.

Question 12

What does electric current create?

Answer 12

A magnetic field

This field can attract or repel magnetic materials. We can use electricity to create motion.

Question 13

What does the right hand slap rule measure?

Answer 13

It determines the direction a wire will move in a magnetic field.

This rule helps predict the motion of the wire based on the magnetic field direction.

Question 14

What does the armature in a motor consist of?

Answer 14

A coil of wire with many loops

This design increases the magnetic field effect.

Question 15

What is the function of brushes in an electric motor?

Answer 15

Connect to the electricity supply

They allow current to flow into the armature.

Question 16

What does a split ring commutator (SRC) do?

Answer 16

It rotates inside the brushes and allows current to ‘switch direction’. This ensures the armature can rotate 360 degrees. This makes DC and no SRC makes AC.

Question 17

What is electromagnetic induction?

Answer 17

The production of voltage when a magnet moves near a wire or a wire moves near a magnet. This is how all dynamos and generators create electricity.

Question 18

What happens when a wire is connected to a sensitive ammeter, and a horseshoe magnet is moved up and down around the wire.

Answer 18

An electric current will flow in the wire

The magnetic field exerts a force on the moving electrons inside the wire.

Question 19

What is alternating current (AC)?

Answer 19

A constantly reversing current

This occurs when the direction of the current changes as the wire moves.

Question 20

How can the voltage driving the current be increased?

Answer 20

• Increasing the speed of movement
• Using a bundle of wires
• Positioning wires at a right angle to the magnetic field

These methods enhance the efficiency of electricity generation.

Question 21

What is a generator?

Answer 21

A device that generates electricity

It can also be referred to as a dynamo or alternator.

Question 22

What type of current does a dynamo generate?

Answer 22

Direct current (DC)

This current flows in one direction only.

Question 23

What type of current does an alternator generate?

Answer 23

Alternating current (AC)

This current alternates direction and can be used to transport electricity through long distances.

Question 24

What is the process of generating electricity from burning coal?

Answer 24

• Heat water
• Create steam
• Turn a turbine
• Generate movement of coils within magnets

This sequence ultimately creates electricity.

Question 25

Free one :)

Answer 25

YAY

Question 26

How did Hans Christian Øersted discover that **electricity** could cause magnetism?

Answer 26

He observed that a wire carrying an electric current caused a compass arrow to move when the current was switch on.

Question 27

What direction does the needle of a compass point to when its placed in the field.

Answer 27

The needle points to the direction of the magnetic field (from the north to the south pole of the magnet).

Question 28

What is an armature

Answer 28

It is a coil of wire that has many loops to increase magnetic field

Question 29

Just like the magnetic field around a magnet, the magnetic field around an electrical wire carrying current has ???

Answer 29

Direction.

Question 30

To create a stronger, straighter magnetic field, what can you do?

Answer 30

Loop a long single current-carrying wire into coils.

Question 31

How do you determine the direction of the magnetic field in a solenoid?

Answer 31

the thumb of the right hand follows the direction of the conventional current flow around the loops (towards the negative terminal) and the fingers give the magnetic field direction through the centre of the solenoid.

Question 32

What does the thumb direction show and what does the other fingers curled show in the right hand grip rule?

Answer 32

To determine the direction of the magnetic field in this case, the thumb of the right hand follows the direction of the conventional current flow around the loops (towards the negative terminal) and the fingers give the magnetic field direction through the centre of the solenoid. ## Footnote The thumb direction shows which way the cureent is flowing and the curled fingers show the direction of the field.

Question 33

What way does the conventional current point in a solenoid?

Answer 33

The conventional current flow points to the north end (or north pole) of the solenoid. (The north pole is negative and conventional current is from positive to negative.)

Question 34

Where does conventional current go?

Answer 34

Conventional current goes from positive to negative.

Question 35

What is the path of the magnetic field around the outside of a solenoid?

Answer 35

The magnetic field around the outside of the solenoid moves out from the north end and around the outside to the south end (just like a bar magnet).

Question 36

What is a bar magnet?

Answer 36

A bar magnet is a rectangular piece of magnetized material, such as iron or steel, with a north pole at one end and a south pole at the other.

Question 37

How do electromagnets work?

Answer 37

Electromagnets work by using electric current to create a temporary magnetic field. If the current is switched on, the core becomes magnetised. If the current is switched off, the magnetic field is reduced and no longer making it a magnet.

Question 38

What has the versatile nature of electromagnets enabled?

Answer 38

The versatile nature of electromagnets has enabled many devices to be invented.

Question 39

What does the magnetic field produced by a current-carrying wire do?

Answer 39

It interacts with the magnetic field surrounding a magnet to exert a force on the wire. This force causes the wire to move.

Question 40

What does the use of brushes and split ring commutators allow?

Answer 40

The use of brushes and split ring commutators allows a loop of wire to rotate.

Question 41

What does the thumb direction, otehr fingers direction and the way the palm is facing mean in the right hand slap rule?

Answer 41

The thumb shows the direction of the current and the other fingers show the direction of the field. The way the palm is facing shows the direction of force.

Question 42

What can be generated from a magnetic field.

Answer 42

Electricity.

Question 43

How do the electrons move through the wire.

Answer 43

The magnetic field exerts a force on the moving electrons inside the wire, which pushes the electrons along the wire. ## Footnote This flow of electrons contributes to an electric current.

Question 44

When the magnet pushes the wire in an opposite direction, what happens?

Answer 44

The electrons are pushed along the wire in the other direction and the current reverses. (Alternating current)

Question 45

What is a more efficient way of generating electricity

Answer 45

To wrap one long wire into a coil and to rotate it in a magnetic field. This is the reverse of an electric motor.

Question 46

What happens if a simple motor is disconnected from the power and made to spin?

Answer 46

It becomes a generator and generates electricity. The faster the coil is spun and the greater the number of turns in the coil, the greater the voltage that is generated. This is called a generator.

Question 47

What are two types of generators?

Answer 47

Dynamos and alternators.

Question 48

Explain how magnetic poles interact, and analyse how two magnetic fields interact to cause attraction or repulsion

Answer 48

Like poles repel and unlike poles attract. This happens because their magnetic fields interact — if the field lines clash (like poles), the magnets repel, but if the field lines connect smoothly (north to south), the magnets attract.

Question 49

Draw magnetic field diagrams

Answer 49

See word document

Question 50

Explain why and how some materials can be magnetized

Answer 50

Some materials can be magnetized because they contain magnetic regions called domains. In unmagnetized materials, these domains point in random directions. When the material is placed in a strong magnetic field, the domains line up, all pointing the same way. This alignment turns the material into a magnet.

Question 51

What are temporary magnet examples?

Answer 51

In materials like iron, nickel, and cobalt, these tiny magnets (domains) can rotate and line up.

Question 52

Compare temporary and permanent magnets

Answer 52

Temporary magnets only stay magnetic while a strong magnetic field is present, and they lose most of their magnetism once it’s removed. Permanent magnets keep their magnetism because their domains stay locked in place even after the external field is gone.

Question 53

Explain what electrical current, voltage and resistance are

Answer 53

Electrical current is the flow of electrons through a wire or circuit. Voltage is the energy or push given to electrons to move. Resistance is how much a material opposes or slows down the flow of electrons.

Question 54

Use symbols to represent the arrangement of components in circuit diagrams

Answer 54

See word document

Question 55

Compare series and parallel circuits

Answer 55

Series: Current goes through one globe then another; if one fails, all turn off. The current is always the same at all points in a series circuit. The lights share the voltage. Parallel: Current splits between branches; if one fails, others still work. The current is split and the current going through each globe is added together for the total current coming from the power source. The lights don’t share the voltage. Series circuits share voltage, while parallel circuits do not.

Question 56

State Ohm’s law and use it to calculate either current, voltage or resistance

Answer 56

V=IR It is the relationship between current, voltage and resistance in a circuit. When voltage is kept constant, current and resistance are inversely proportional. This means that doubling the resistance will halve the current or that halving the resistance will double the current.

Question 57

Describe magnetic fields produced by electric currents

Answer 57

An electric current is made of moving electrons, and moving charges produce a magnetic field. So when electrons flow through a wire, their motion generates a magnetic field around the wire.