Electric and Magnetic Fields

Question 1

How is an electric field created?

Answer 1

Around any electrically charged object.

Question 2

What do magnets produce?

Answer 2

Magnetic field.

Question 3

What are the two poles?

Answer 3

North and South

Question 4

How can you show a magnetic field through a drawing?

Answer 4

Magnetic field lines or line of flux with arrows

Question 5

Where do the lines go from to?

Answer 5

North to South

Question 6

What does it mean if the lines are closer together?

Answer 6

There is a strong magnetic field.

Question 7

Where is the magnetic field strongest at?

Answer 7

The poles of magnets

Question 8

What happens when similar poles meet?

Answer 8

They repel each other

Question 9

What happens when different poles meet?

Answer 9

They attract each other

Question 10

What elements are magnetic?

Answer 10

Iron, nickel, cobalt and steel

Question 11

What is a permanent magnet?

Answer 11

Produce their own magnetic field all the time

Question 12

What is an induced magnet?

Answer 12

Only produce a magnetic field when in another magnetic field

Question 13

What is an advantage of induced magnets?

Answer 13

They can be turned off and on

Question 14

How does current create a magnetic field?

Answer 14

When current flows through a long straight conductor a magnetic field is created

Question 15

What is the magnetic field around a wire like?

Answer 15

It has concentric circles perpendicular to the wire.

Question 16

What does the right hand rule show?

Answer 16

It shows the direction of the magnetic field.

Question 17

What does the thumb represent in the right hand rule?

Answer 17

The direction of the current

Question 18

What does the fingers that curl in the right hand rule represent?

Answer 18

The direction of the magnetic field.

Question 19

How is the magnetic field within in a solenoid?

Answer 19

Strong and uniform

Question 20

It is useful traits of electromagnets?

Answer 20

They are only magnetic when you keep the current flowing in the wire.
It can also be reversed when the current changes direction.

Question 21

What are the four ways you can increase the strength of an electromagnet?

Answer 21

• Increase the current
• Increase number of turns in the coils
• Decrease length of coil
• Add iron core

Question 22

What is the motor effect?

Answer 22

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

Question 23

What does the thumb represent in the left hand rule?

Answer 23

Direction of the force

Question 24

What does the first finger represent in the left hand rule?

Answer 24

Direction of the magnetic field

Question 25

What does the second finger rule represent in the left hand rule?

Answer 25

Direction of the current

Question 26

What is the formula for force?

Answer 26

Magnetic flux density x Current x Length | F = B x I x L (lower case)

Question 27

What does step up transformers do?

Answer 27

- Increases the voltage to around 400,000 - Decreases current - Increase p.d - More number of coils - Less energy wasted

Question 28

What does step down transformers do?

Answer 28

- Decreases the voltage - Increases current - Decrease in p.d - Less number of coils - Safe for house to use

Question 29

What do isolating transformers do?

Answer 29

- No change in p.d. - Used for safety - isolated from a circuit from the rest of the household current

Question 30

How is static built up?

Answer 30

- By friction - certain insulating materials are rubbed together - negative charge will be scrapped off one onto the other - the material that loses electrons becomes positively charged -

Question 31

How are electrons able to move to create static electricity?

Answer 31

- The material are insulators | - electrons can move

Question 32

What is the function of a dynamo?

Answer 32

- Generate direct current

Question 33

What happens in a dynamo?

Answer 33

- the generators apply a force to rotate a coil in a magnetic field - as the coil spins - a current is induced

Question 34

How can you increase the strength of an electromagnet?

Answer 34

- change the current | - increase the number of turns in a wire

Question 35

What are the factors that affect the size of the force?

Answer 35

- changing current - changing the strength of magnet - changing angle between wire and magnetic line