Physics: 12. Magnetism
Please remember to photocopy 4 pages onto one sheet by going A3→A4 and using back to back on the photocopier
OP45 Carry out simple experiments to show attraction and repulsion between magnets, and test a variety of materials for magnetism
OP46Plot the magnetic field of a bar magnet
OP47 Demonstrate that the Earth has a magnetic field, and locate North and South.
To show attraction and repulsion between magnets
1. Hang a magnet as shown (the dark half represents the north-pole). 2. Bring another magnet up close to it.
3. Notice that if you bring up a north pole it repels the north of the first magnet, but if you bring up the south-pole end it attracts the north-pole of the first magnet. Conclusion:
Similar poles repel, opposite poles attract
To test a variety of materials for magnetism
To test a material for magnetism bring a magnet up to the material and see if the material becomes attracted to the magnet.
To demonstrate that the Earth has a magnetic field, and locate North and South.
When we allow magnets to hang free, they come to rest with one end facing north and the other facing south. We therefore label the north-facing end ‘the North Pole’, and the south-facing end ‘the South-Pole’. ‘pole’ means ‘end’.
Uses of magnets
Fridge magnets, in motors, in speakers
To visualise the magnetic field around a bar magnet
1. Place a bar magnet on a bench and place a page on top.
2. Gently sprinkle iron filings over the page.
3. The filings with take the shape of the magnetic field.
1. Cover the magnet in cling film first to prevent the filings accidently sticking to the magnet. 2. Spray paint over the patterm to make a permanent pattern.
To plot the magnetic field of a bar magnet
Equipment: Magnet, sheet of paper, compasses
i) Place the plotting compass beside the magnet and mark the position of the north end. ii) Move the position of the compass and repeat a number of times on both sides of the magnet. iii) Join the dots.
Result: a pattern is formed on the paper representing the magnetic field of the magnet.
The lines joining the North and South poles are called magnetic field lines; they are most concentrated at the poles.
Magnetic field lines are drawn going from north to south.
1. [2010 OL]
The diagram shows the north pole of one magnet being brought up to the north pole of a freely suspended magnet. i) What would you expect to happen to the freely suspended magnet? ii) What does this tell us about like poles?
2. [2007 OL]
The diagram shows a magnet freely suspended from a wooden stand. |Repel |
Complete the statements below using the correct word from the list on the right in each case. i) When the north pole of another magnet is brought close to the north pole of the hanging magnet they will ___________ each other. ii) When the south pole of another magnet is brought close to the north pole of the hanging magnet they would _____________ each other.
3. [2006 OL][2009 OL]
The diagram shows a bar magnet.
i) Draw the pattern made if iron filings or plotting compasses were placed around the bar magnet. ii) Give one use of a magnet.
The diagram shows the outline of a bar magnet.
i) Draw two magnetic field lines one on each side of the bar magnet. ii) What are the parts labelled N and S in the diagram called?
5. 2011 [OL]
The diagram shows a bar magnet
i) What does the letter N on the magnet mean?
A student wanted to show the pattern of the magnetic field around a bar magnet. ii) Name a substance or a piece of equipment used in the laboratory to show the pattern of the magnetic field around a magnet. iii) Write the letter P below the pattern you would expect to get if you did this experiment.
6. [2008 OL]
Describe, with the help of a labelled...