magnets and electromagnets - lesson 1

Target: to know about magnetic materials and about the properties of magnetic poles.

Wednesday 12 April 2023

Lesson 1

Material Prediction Observation

Electromagnetism : Magnetic?

Which of the metals below are magnetic metals?

Aluminium(Al)

Silver (Ag)

Iron

(Fe)

Gold (Au)

Nickel (Ni)

Cobalt (Co)

Copper (Cu)

Zinc(Zn)

Magnesium (Mg)

Al ZnAg

Cu

Au

Mg

Electromagnetism : Magnetic?

N

S

Fe

NiCo

Only Iron [Fe], Nickel [Ni] and Cobalt [Co] are.

Not all metals are magnetic Iron, cobalt, nickel and steel are

magnetic

Non magnetic materials include; Copper, Aluminium, Magnesium All non metals

Key points

1

2

3

Attract

Repel

Repel

A magnet has 2 ends called poles They are known as North and South

They line up with the Earth’s magnetic field

Like poles repel and unlike poles attract

Magnets are made of either iron, nickel or cobalt

Only a magnet will be repelled by another magnet

Non magnetic objects are neither repelled or attracted to magnets

Key points

A compass needle is a small magnet with a North pole, N, and a South pole, S.

Ruth placed two compasses onto a piece of card.Both compass needles pointed in the direction shown below.

N

S

N

S

card

com pass

com passneedle

(a) Joan placed a bar magnet with its South pole between the two compasses.The compass needles moved as shown below.

On the diagram below, label the North pole and South pole of each compass needle.Use the letters N and S.

bar m agnet

(b) Joan turned the bar magnet round so that the North pole was between the two compasses.

On the diagram below, label the North pole and South pole of each compass needle now.Use the letters N and S.

bar m agnet

(c) Joan repeated her experiment with an aluminium bar instead of a bar magnet.

What happened to the compass needles? ....................................................................

.................................................

(a) Ann put a paper cup into a glass beaker.She glued a magnet in the bottom of the paper cup.She glued another magnet in the bottom of the beaker.The magnets repelled.

N

S

S

N

m agnet

m agnet

paper cup

glass beaker

What two forces act on the paper cup and its contents to keep it in this position?

1. ........................................................... 2. ...........................................................

(b) Ann put 5 g of aluminium rivets into the paper cup.It moved down a little as shown in diagram B.

N

S

S

N

alum iniumrivets

Ann plotted a graph to show how the mass of aluminium rivets affected the distance the cup moved down.

6

5

4

3

2

1

00 10 20 30 40 50 60

m ass (g)

d istance papercup m oveddown (m m )

(i) Use the graph to find the mass that made the cup move down 4 mm.......... g

(ii) Why did the graph stay flat with masses greater than 40g?

(c) Ann removed the 5 g of aluminium rivets and put 5 g of iron nails into the cup.

N

S

S

N

ironnails

The paper cup moved down more with 5 g of iron nails than with 5 g of aluminium rivets as shown in diagram C.Give the reason for this.

.....................................................................................................................

.....................................................................................................................

1. What is the ‘Pole Star’? 2. What is ‘True North’? 3. What is ‘Magnetic North’? 4. What is the ‘Southern Cross’? 5. Where does the word ‘news’ come

from?