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Question 1

What does an electric current in a material produce?

Answer 1

A magnetic field around it

Question 2

How can you use iron fillings to see magnetic field patterns of a magnet?

Answer 2

Just put the magnet under a piece of paper and scatter the iron fillings on top. The iron fillings will align themselves with the field lines.

Question 3

What are permanent magnets?

Answer 3

They are objects that are always magnetised

Question 4

How can you use a compass to plot magnetic field patterns?

Answer 4

Put the magnet on a piece of paper and place the compass on the paper, next to the magnet. The compass needle will point in the directions of the field line at this position. Mark the direction that the compass needle is pointing in by marking two dots on the paper, one at each end of the needle .
Move the compass so that the tail end of the needle is where the tip of the needle was previously. Repeat this and then join up the marks you made- you will end up with a drawing of one field line around the magnet.
Repeat this method at different points around the magnet to get several field lines.

Question 4

Magnetic field have magnetic flux. What does magnetic flux mean?

Answer 4

The amount of energy flow

Question 6

When an induced magnetic is not in a magnetic field…

Answer 6

…their regions/domains are not ‘lined’ up.

Question 7

What happens to the magnetic field as the electric current gets larger?

Answer 7

The magnetic field gets stronger

Question 9

What are hard magnetic materials?

Answer 9

Materials whose domain keep lining up after being removed from a magnetic field.

Question 10

When an induced magnet is in a magnetic field…

Answer 10

…their regions line up

Question 11

The closer their field lines are too each other…

Answer 11

…the stronger the magnetic field at that point

Question 12

Why is using a compass better than using iron fillings to find the magnetic field lines?

Answer 12

Using a compass is better than iron fillings as the drawing of the field will still be there after the magnet has been removed and the drawing also shout the direction of the magnetic field lines. Also iron fillings are quite messy to work with as they are incredibly difficult to take off a magnetic if they get in contact with it.

Question 13

What direction will compasses always point when they aren’t near a magnet? What is this evidence of?

Answer 13

Compasses will always point north when they aren’t near a magnet.
This is evidence that the earth has a magnetic north and South Pole and therefore must have a magnetic core.

Question 14

What are induced magnets?

Answer 14

They are objects that become magnetised when placed in a magnetic field.

Question 15

Define a magnetic field

Answer 15

A magnetic field is a region where a magnetic material experiences a force

Question 16

What are permanent magnets made of?

Answer 16

Permanent magnets are made of many small magnetic regions called domains that are all ‘lined’ up.

Question 18

What are soft magnetic materials?

Answer 18

Materials whose domain who domains return to their previous orientation after being removed from a magnetic field.

Question 19

Why do compasses have pointers that must be weighted?

Answer 19

So that it can assume the angle between Earth’s magnetic field lines and lines horizontal to the surface of the Earth.

Question 20

Magnetic fields have magnetic flux density. What is magnetic flux density?

Answer 20

The number of field lines passing through a specific area.
We also call this magnetic field strength.
It is measured in teslas (T).

Question 21

What direction do the magnetic fields flow when the current flows towards you with a straight wire carrying current? What about if the current if flowing away from you?

Answer 21

With a straight wire carrying current…

…the magnetic field lines flow anti-clockwise when surrender flows towards you.

…the magnetic fields line flow clockwise when current flows away from you.

Question 22

What is a magnetic field around a straight current-carrying wire made up of ?

Answer 22

A magnetic field around a straight current-carrying wire is made up of concentric circles with the wire in the centre.

Question 23

Describe the relationship between magnetic field strength and distance from wire.

Answer 23

It is non-linear relationship- the strength des creases quickly at first but this slows down with an increasing distance.

Question 24

What is a solenoid?

Answer 24

Many parallel loops joined together.

Question 25

If you have lots of coils of wire joined together to make a solenoid…

Answer 25

The magnetic effect is increased

Question 26

The magnetic field inside a current carrying solenoid is…

Answer 26

…strong and uniform

Question 27

Outside the coil, the field is just like the one around a bar magnet. What does this mean?

Answer 27

This mean that the end of a solenoid act like the North Pole and South Pole of a bar magnet.

Question 28

What is an electromagnet?

Answer 28

A solenoid is an electromagnet because a magnetic field is created when it is carrying current and its tow end like the North Pole and the South Pole.

Question 29

The magnetic effect at the ends of the solenoid will increase if…

Answer 29

• the current in the wire is increased
• the number of turns (i.e the number of coils) of wire is increased, but the length stays the same
• the cross-sectional area of the solenoid is decreased
• the length of the solenoid is decreased (but the number of turns stay the same)
• an iron core is added inside the solenoid

Question 30

Which is stronger, a electromagnet or a permanent magnet?

Answer 30

Electromagnet

Question 31

What is the equation to calculate the force on a current carrying conductor when it’s at a right angles to a magnetic field?

Answer 31

Force on a
conductor = magnetic flux density (T) x current (A) x length (m)
carrying
a current (N)

Question 32

What is produced when you combine the field due to a wire with the field due to a permanent magnet?

Answer 32

It produced a force.

Question 33

When a current-carrying conductor (e.g a wire) s put between magnetic poles, the two magnetic fields affect one another. The result is…

Answer 33

a force on the wire.

Question 34

Where should the wire be between magnetic poles to experience the full force?

Answer 34

To experience the full force, the wire has to be a 90 degrees (right angles) to the magnetic field.

Question 35

If the wire runs along the magnetic field of the magnetic poles..

Answer 35

It won’t experience any force at all.

Question 36

How can you change the direction of the force when a current carrying conductor is out between magnetic poles?

Answer 36

The force always acts in the same direction relative to the magnetic field of the magnets and the direction of the current in the wire. So changing the direction of either the magnetic field or the current will change the direction of the force.

Question 37

Explain Fleming’s left-hand rule.

Answer 37

It is used to find the direction of the force on a current-carrying conductor.
Point for index finger on your left hand in the direction of the magnetic field and your second finger in the direction of the current. Your thumb will then pinky in the direction of the force.

Question 38

What is a split ring commutator?

Answer 38

A split ring commutator enable the current to flow the same way from the batter, but change to different halves of the coil as it spins.