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3.1 Identify magnetism as a non-contact force, and correctly use the term “magnetic field.”
3.2 Describe and draw a diagram to represent the magnetic field around a bar magnet.
3.3 Predict and describe the behaviour of like and unlike magnetic poles brought close together.
3.4 Describe some uses of magnets and electromagnets in technology and industry.
I can...
3.1 Identify magnetism as a non-contact force, and correctly use the term “magnetic field.”
Part A: View video
Grogu Summons a Force Field https://www.youtube.com/watch?v=mLII-x1_qT4 [0.58 mins]
Answer the questions with your partner:
What do we mean by force field?
Do force fields exist?
Don't we need to touch something for a force to act? Think of some examples to explain your answer.
Part B: Look at the image.
What is happening?
What do you think the ball is?
Is this a contact force or a non-contact force?
The ends of a magnet are called poles.
If a magnet floats in water, then one end spins to face the Earth’s north pole. This end is the north pole of the magnet. The opposite pole of the magnet is the south pole.
If a magnet is cut in half, each half still has a north and a south pole.
The magnetic field is strongest at the poles of a magnet.
Opposite - unlike - magnetic poles attract each other.
Same - like - poles push away, or repel each other.
Many toys involve magnets. However, safety of the toy and age suitability need to be considered.
What is dangerous to young children about magnets?
What effect can a magnet have if swallowed?
Many toys involve magnets. However, safety of the toy and age suitability need to be considered. See Tx p307
What is dangerous to young children about magnets?
What effect can a magnet have if swallowed?
What causes magnetism?
How can you make a permanent magnet?
Using the mini magnets,to identify which substances magnets attract:
predict
test it
Using the mini magnets to identify which substances magnets can attract iron filings in a Ziplock bag through:
predict
test it
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3.2 Describe and draw a diagram to represent the magnetic field around a bar magnet.
The space around a magnet where a magnetic force is experienced shows lines of magnetic force. This is called a magnetic field.
You cannot see a magnetic field, but you can observe its effects.
A force is exerted on a magnetic material when it is brought into a magnetic field.
The force is a non-contact force because the magnet and the material do not have to touch each other, the force acts at a distance.
It would be difficult to draw the results from the sort of experiment below, so we draw simple magnetic field lines instead. Field lines:
have an arrowhead on them
never cross each other
come out of the North pole and go into the South pole, with the arrow pointing to South
are more concentrated at the poles
represent a stronger magnetic field when they are bunched closely together
represent a weaker magnetic field when they are spaced further apart
bbc.co.uk/bitesize/guides/z3g8d2p/revision/2
Complete experiment
Place some iron filings in a Ziplock bag and ensure that the zip is securely fastened.
Place the bag over the bar magnet and move the bag.
Draw the shape of the filings.
Repeat for the horseshoe magnet.
Draw lines of force. Remember, magnetic field lines:
do not cross
always run from the North to the South pole of a magnet, with the arrow pointing to South
represent a stronger magnetic field when they are bunched closely together
represent a weaker magnetic field when they are spaced further apart
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3.3 Predict and describe the behaviour of like and unlike magnetic poles brought close together.
Use the magnets to identify what happens when you bring together
two North poles
two South poles
a North and a South pole
Develop rules for magnetic poles:
Two poles of the same type..........
Two different poles ..............
View video [0.51 mins] Attraction & Repulsion
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3.4 Describe some uses of magnets and electromagnets in technology and industry.
In 1820, the Danish scientist Hans Oersted (1777–1851) made an unexpected discovery. While explaining to his students that he did not believe there was any link between magnetism and electricity, he placed a compass near a wire through which an electric current was flowing. To his surprise, he saw the compass needle move. Oersted realised that electricity flowing through a wire creates a magnetic field around it. If the wire is wound into a coil, it produces a much stronger magnetic field. Inserting a piece of iron inside the coil increases its strength even further. Such a device is called an electromagnet. It acts like a bar magnet.
An electromagnet is a temporary magnet, because when the electricity in the wire is switched off, the magnetic field is also switched off.
youtube.com/watch?v=_odHVX4mUAQ
Read the information
View video [2.11 mins] How to Make an Electromagnet
In 1820, the Danish scientist Hans Oersted (1777–1851) made an unexpected discovery. While explaining to his students that he did not believe there was any link between magnetism and electricity, he placed a compass near a wire through which an electric current was flowing. To his surprise, he saw the compass needle move. Oersted realised that electricity flowing through a wire creates a magnetic field around it. If the wire is wound into a coil, it produces a much stronger magnetic field. Inserting a piece of iron inside the coil increases its strength even further. Such a device is called an electromagnet. It acts like a bar magnet.
An electromagnet is a temporary magnet, because when the electricity in the wire is switched off, the magnetic field is also switched off.
In groups of 1-3:
Research one use of a magnet/electromagnet in electronics, commerce or industry.
Prepare a 2-3 minute oral presentation for the class.
A. Read the summary cards at right
[7 mins preparation time, then 7 mins presentation time]
Taking turns with the ideas below, (first person the one whose first name starts with the letter earlier in the alphabet), explain to a partner - use diagrams, gifs, video clips if you like.
The area around a magnet, where a magnetic force is experienced, shows lines of magnetic force.
You cannot see a magnetic field, but you can observe its effects.
A non-contact force is exerted on a magnetic material when it is brought into a magnetic field.
If a magnet is cut in half, each half still has a north and a south pole.
Complete Live Worksheet Bar Magnets and Live Worksheet Magnets Are Everywhere below
Complete from Text p313 Q11, 12, 13 combination A, 16
Complete this short quiz.
Complete from Text p313 Q11, 12, 13 combination A and B, 16, 17