Electromagnetism

Question 1

what are the two types of electromagnetism?

Answer 1

Permanent magnets

Temporary magnets

Question 2

what happens when the magnetising field has been removed?

Answer 2

• The magnetism either stays or decays partially or fully depending on the magnetic material

Question 3

what is magnetic remeance?

Answer 3

it is the degree of residual magnetisation that remains once the magnetic field is removed

Question 4

Materials which are required to retain their magnetism will have high magnetic remaence and as such are used to make permanent magnets

whilst those materials required to lose their magnetism quickly, such as soft iron cores for relays and solenoids, will have a very low magnetic remaence

True or false?

Answer 4

true

Question 5

All magnets have two regions called magnetic poles (referred to as North and South poles) which are connected by invisible lines of flux. TRUE OR FALSE?

Answer 5

TRUE

Question 6

These lines of flux (called a vector field) can not be seen by the naked eye, but they can be seen visually by using iron fillings sprinkled onto a sheet of paper or by using a small compass to trace them out. TRUE OR FALSE?

Answer 6

TRUE

Question 7

what is the unit of a magnetic flux?

Answer 7

It is a webber (wb)

Question 8

The lines which go to make up a magnetic field showing the direction and intensity are called Lines of Force or more commonly “Magnetic Flux”. TRUE OT FALSE?

Answer 8

TRUE

Question 9

where is the magnetic field strongest?

Answer 9

is strongest near to the poles of the magnet where the lines of flux are more closely spaced

Question 10

what happens to unlike- and like poles?

Answer 10

Unlike poles attract

Like poles repel

Question 11

What is electromagnetism?

Answer 11

Electromagnetism is produced when an electrical current flows through a simple conductor such as a piece of wire or cable

Question 12

A circular electromagnetic field is generated around the conductor with the direction of rotation of this magnetic field governed by the direction of the current flowing through the conductor. TRUE OR FALSE?

Answer 12

TRUE

Question 13

what is the equation for magnetic field intensity (H) in a conductor wire?

Answer 13

H=i/2piR

Question 14

what is the equation for magnetic field intensity in a current loop?

Answer 14

H=i/2a

Question 15

what is a solenoid?

Answer 15

a super coiled wire