P4.1

Question 1

Two types of forces

Answer 1

Contact or non-contact

Question 2

What is a magnet

Answer 2

A magnet is any object that has magnetic field around it.

Question 3

The Closer the field lines…

Answer 3

The stronger the magnet

Question 4

What is a permanent magnet

Answer 4

A permanent magnet is one which always has amagnetic field around it.

Question 5

What happens when a non magnet is brought close to a magnet

Answer 5

The non-magnets have magnetism induced in them when the permanent magnet is brought close.i.e. a non magnetic material can sometimes be temporarily made magnetic, and thus will attract (repel) other permanent magnets.

Question 6

Direction of magnetic field lines

Answer 6

Magnetic field lines go from the North pole to the South pole of a magnet.

Question 7

do field lines cross

Answer 7

NO NEVER THATS WRONG OMG

Question 8

What is a magnetic field

Answer 8

A region of space within which magnets and magnetic materials experience a magnetic force of attraction or repulsion.

Question 9

What happens when current flows in a wire

Answer 9

A magnetic field is created around it

Question 10

What do the magnetic field lines around a current carrying wire look like

Answer 10

Like concentric rings

Question 11

How do you work out direction of magnetic field lines

Answer 11

Corkscrew rule - RIGHT HAND ONLY

Question 12

What is a solenoid

Answer 12

A solenoid is a device that acts to increase the strength/size of the magnetic field around a current carrying wire.

Question 13

Solenoids are used to produced what type of magnet

Answer 13

Electromagnet

Question 14

How is a solenoid made

Answer 14

A wire is looped many times around a piece of metal (not a magnet!) that can be magnetised (iron which is magnetic material)

Question 15

What is an electromagnet

Answer 15

A magnet which runs on electricity (electric current).

An electromagnet’s magnetic field can be switched on and off, by switching the current on and off.

Question 16

Factors that effect electromagnets

Answer 16

1. The number of coils in the wire.
2. The size of the current through the wire.
3. Changing the material of the core inside the coils.

Question 17

Magnetic metals

Answer 17

Iron
Cobalt
Nickel

Question 18

two types of magnets

Answer 18

Permanent magnets
Induced magnets

Question 19

Permanent Magnets

Answer 19

made out of permanent magnetic materials, for example steel

will produce its own magnetic field

It will not lose its magnetism

Question 20

Examples of permanent magnetic material

Answer 20

Steel

Question 21

Induced Magnets

Answer 21

When a magnetic material is placed in a magnetic field, the material can temporarily be turned into a magnet

Question 22

Special about induced magnetism

Answer 22

Magnetic materials will always be attracted to a permanent magnet - ALWAYS HAVE OPPOSITE POLE to magnets closest pole

Question 23

When the induced magnetic material is removed from the magnetic field…

Answer 23

lose most/all of its magnetism quickly

Question 24

Earth

Answer 24

Question 25

Factors Affecting Magnetic Field Strength

Answer 25

The size of the current The distance from the long straight conductor (such as a wire)

Question 26

How to find the polarity of each end on the solenoid

Answer 26

If the current is travelling around in a clockwise direction then it is the South Pole If the current is travelling around in an anticlockwise direction then it is the North Pole

Question 27

To increase strength of solenoid - add core of what

Answer 27

Iron

Question 28

Why iron

Answer 28

The iron core will become an induced magnet when current is flowing through the coils The magnetic field produced from the solenoid and the iron core will create a much stronger magnet overall

Question 29

What is a soft magnetic material

Answer 29

easy to magnetise but also easily lose their magnetisation.

Question 30

Example of a soft magnetic material

Answer 30

Iron

Question 31

What is a hard magnetic material

Answer 31

difficult to magnetise but once they are magnetised, they are difficult to demagnetise.

Question 32

Example of a hard magnetic material

Answer 32

Steel

Question 33

Uses of soft magnetic material

Answer 33

Electromagnets - turn on and off quickly (iron core)

Question 34

Uses of soft magnetic material

Answer 34

Permanent Magnets

Question 35

What is an electromagnet

Answer 35

consists of a long coil or solenoid wound around a core made from a soft magnetic material such as iron.

Question 36

Differences between electromagnet + permanent magnet

Answer 36

Question 37

The core of an electromagnet is made from a soft magnetic material. Why would a hard magnetic material be unsuitable for this purpose?

Answer 37

Hard magnetic materials are difficult to magnetise so they would not create a strong magnetic field when the current is switched on. Once magnetised, they retain their magnetisation so it would not be possible to switch the electromagnet off.

Question 38

Why is there a limit to how much current you can put through an electromagnet

Answer 38

results in a strong heating effect that could melt the insulation - use a superconducting coil (coils of zero resistance)