Download All about Magnets

ALL ABOUT MAGNETS - Mr. Hung 2013
1. A Magnet can attract some metals, including IRON, COBALT and NICKEL. They are called
magnetic metals. Each metal can be made into magnet.
2. A Magnet can attract Steel, which is an alloy with mainly iron and 1-2% carbon.
3. A Magnet produces a magnetic field or force. The field can be visualised by dusting iron filing on
a piece of paper over a bar magnet.
4. Magnetic field or force is known as a NON-CONTACT force as the force has the effect without
actually touching other object.
5. A Magnet has strongest fields at its poles, known as North and South poles.
6. When a Magnet is broken into a few pieces, each piece will remain having a north and a south
poles.
7. Each magnet is actually consists of tiny micro-magnet (or domains) orderly line up from north
to south poles within the magnet.
8. LAWS of Magnetism:
(1) Like (Same) Poles repel, eg. A north and a north poles
(2) Opposite Poles attract, eg. A north and a south pole
9. A compass consists of a needle which is actually a magnet.
10. The Earth also acts like a giant magnet consisting of a North and a South Poles. It consists
mainly iron and nickel.
11. A compass will be able to show where the North pole is.
12. A permanent magnet can be used to magnetise a needle or a nail by stroking it in one direction
30-40 times – a temporary magnet is created.
13. If you float the needle over a cork or polystyrene on water, the needle will point at the North
pole like a compass.
14. You can also magnetise a nail by wrapping it with a wire and passing electricity through – an
electromagnet. This is only a temporary magnet, when the electricity is cut off, the magnetism of
the nail will decrease or lose.
15. A magnet can be destroyed by 2 methods – hammering and heating. Any of this method makes
the domains arranged in different direction (disorientated), this destroy the magnetism.
16. There are many uses of magnets:
fridge magnet, fridge magnetic door, cabinet door magnet, hand bag magnet, speaker, telephone,
Liquid Crystal Display LCD, compass, acupuncture device, alarm, motor in toys, electrical
generator, credit card, computer cord and cover, name tag, scrap yard, Magnetic Resonance
Imaging MRI, Magnetic Levitation Train (MLT).
Year 7 Science Homework - All About Magnets
Name: __________________________ Form: _______
Answer the questions below: [ marks/ points given]
1. Name the only 3 metals that can be made into magnets. [3]
2. What is steel? How come steel can become magnetic?
3. What happens when you spread iron filings over a piece the paper with a bar magnet placed
underneath? Draw the diagram to demonstrate. [1 + 3]
4. Is Magnetic Force a Contact and an non-contact force? Explain your answer (1 + 1]
5. The magnet is strongest at their ________________. They are the _____________ and ________________
Poles. [3]
6. What can be found inside a bar magnet? Can you draw a diagram to illustrate it? [1 + 2]
7. What are the 2 laws of Magnetism? Use 2 diagrams to explain the answer [2+2]
8. How can you magnetise a needle? [2]
9. How can you make an electromagnet using a nail? [2]
10. Give 2 methods that can demagnetise a magnet. [2]
11. Give 5 daily examples of magnets. [5]