Physics Topic 7

Question 1

A magnet is any material or object that produces a ________ field.

Answer 1

magnetic

Question 2

Give 3 examples of magnets:

Answer 2

The Earth
A horseshoe magnet
A bar magnet

Question 3

The arrows on the magnetic field lines always point:

Answer 3

Out from the north and into the south

Question 4

The strength of a magnetic field is shown by the _______ of the magnetic field lines.

Answer 4

density

Question 5

Magnetic field lines can show (Give 2):

Answer 5

-> Whether two magnets would attract or repel
-> The strength of the magnet at a particular point
-> The direction that a small compass would point at that point

Question 6

How can you tell which parts of the magnet diagram has the strongest magnetic field strength?

Answer 6

Field lines which are closer together

Question 7

A magnetic m_______ is any material or object that can be influenced by a magnetic field, and has the potential to become a magnet.

Answer 7

material

Question 8

Which of the following elements are magnetic?
Iron
Nickel
Copper
Cobalt

Answer 8

Iron
Nickel
Copper
Cobalt

Question 9

Which type of magnetism is it when a magnetic material temporarily becomes a magnet when it’s placed close to a permanent magnet?

Answer 9

Induced magnetism

Question 10

Permanent magnets always produce their ___ magnetic field
Temporary / induced magnets only produce a magnetic field in the ________ of another magnet

Answer 10

Permanent magnets always produce their own magnetic field
Temporary / induced magnets only produce a magnetic field in the presence of another magnet

Question 11

The force between a permanent and an induced magnet will:

Answer 11

Always be attractive

Question 12

Magnetic materials that gain and lose magnetism quickly are called magnetically ____ materials.
Magnetic materials that gain and lose magnetism slowly are called magnetically ____ materials.

Answer 12

soft
hard

Question 13

An example of a magnetically soft material is ____.
And example of a magnetically hard material is _____.

Answer 13

iron
steel

Question 14

When an e_______ current flows through a material, a magnetic field is always p_______

Answer 14

electrical
produced

Question 15

The right hand rule can tell us the…

Answer 15

… direction of the magnetic field induced by a flowing current.

Question 16

In the _____ ____ rule, the thumb is placed following the same direction as the c______ is travelling, and the fingers are the curled in the direction of the magnetic field l____.

Answer 16

right hand
current
lines

Question 17

In an electromagnet, a current is required to produce the magnetic field.
When the current is switched off, the magnetic field:

Answer 17

disappears

Question 18

Describe the 3 ways to increase the strength of an electromagnet.

Answer 18

Increase the current
Increase the number of turns in the solenoid, while keeping the length the same
Reduce the length of the solenoid while keeping the number of turns the same
Add a soft iron core

Question 19

What is the motor effect?

Answer 19

A current carrying wire in the presence of a magnetic field will experience a force.

Question 20

To experience the full force, a current carrying wire must be placed _____________ to the magnetic field.

Answer 20

perpendicular

Question 21

Fleming’s left hand rule can be used to tell us…

Answer 21

… the direction of the force experienced by a current carrying wire in a magnetic field.

Question 22

Fleming’s Left Hand Rule)
The thumb represents…

Answer 22

The direction of the force

Question 23

Fleming’s Left Hand Rule)
The index represents…

Answer 23

The direction of the magnetic field

Question 24

Fleming’s Left Hand Rule)
The middle represents…

Answer 24

The direction of the current

Question 25

The magnetic field strength (also known as magnetic flux density) is measured in:

Answer 25

Teslas (T)

Question 26

A wire carrying a current of 2 A is perpendicular to a magnetic field of 15 T. The length of the wire in the field is 0.2 m.
What is the force experienced by the wire?

Answer 26

2 x 15 x 0.2 = 6N

Question 27

A wire carrying a current of 6 A is perpendicular to a magnetic field of 30 T. The length of the wire in the field is 0.1 m.
What is the force experienced by the wire?

Answer 27

6 x 30 x 0.1 = 18N

Question 27

How does the split ring commutator ensure the coil rotates in one direction? 4 steps

Answer 27

1) The split-ring commutator swaps the positive and negative connections every half turn.
2) Therefore, the direction of the current through the coil reverses every half turn.
3) This means that the forces acting on the coil will always be acting in the same direction.
4) This causes the coil to rotate continuously in one direction.

Question 28

Overall, electric motors use e__________ to create a rotational m_____.

Answer 28

electricity
motion

Question 29

Give 2 ways to increase the speed of rotation in an electric motor:

Answer 29

Add more turns to the coil
Increase the magnetic field strength / magnetic flux density of the magnet
Increase the current in the coil