Magnetism and Electromagnets A2 36-43

Question 1

Name the 2 poles of a magnet

Answer 1

North and South pole

Question 2

What are some magnetic materials?

Answer 2

Iron, cobalt, steel, nickel

Question 3

What are magnetic field lines?

Answer 3

Lines drawn to represent the magnetic field

Question 4

State 2 methods to find the shape of a magnetic field

Answer 4

• Using plotting compasses
• Using iron fillings

Question 5

How do
methods of finding the shape of the magnetic field work?

Answer 5

The direction of the compass and iron fillings point towards the direction of the magnetic field, they go from north to south. The closer the field lines, the stronger the magnetic field.

Question 6

How does the earth behave?

Answer 6

As though there is a huge bar magnet inside it.

Question 7

How can you make an electromagnet?

Answer 7

Make a circular loop of wire and pass a current through it. The centre of the loop’s field lines will be straight

Question 8

How can you make this electromagnet stronger?

Answer 8

Make multiple loops to form a coil, called a solenoid. When you run a current through it, it becomes an electromagnet.

Question 9

What is a core in an electromagnet and what does it do?

Answer 9

A core is a material placed in the centre of an electromagnet to make it much stronger.

Question 10

What are most cores made of?

Answer 10

Steel and iron

Question 11

1. ____ is easy to magnetise, but loses its magnetism easily
2. ____ is hard to magnetise, but has its magnetism for a long time.

Answer 11

1. Iron
2. Steel

Question 12

State 3 things that affect the strength of an electromagnet

Answer 12

• The number of turns/loops in the coil
• The amount of current flowing through
• The material used at the core

Question 13

State the 2 differences between electromagnets and permanent magnets

Answer 13

• Electromagnets can be turned off and on.
• Electromagnets can be made much stronger than permanent magnets.

Question 14

How does the strength of an electromagnet vary with distance from the magnet

Answer 14

The strength of the magnetic field decreases as the distance from the electromagnet increases.

Question 15

What is the magnetic field of a solenoid similar to?

Answer 15

The magnetic feild around a bar magnet.

Question 16

How does a doorbell work?

Answer 16

1. When the switch is pressed, the circuit is activated, the metal armature gets attracted to the activated electro magnet.
2. Then the circuit gets broken, making the armature returning to its original position, the springy metal also returns to its original position, making the bell ring once.
3. Then once again, the circuit gets completed, current flows again and the cycle repeats

Question 17

How do earphones work with the help of electromagnets.

Answer 17

1. The electric current from you phone or mp3 player is transferred through the wire to a coil.
2. The magnetic strength of the coil changes, making the magnet attract and repel, moving the cone in and out making sound