Primary 3 Science · Answers and explanations
Making Magnets
Use this page to check the worksheet together. Talk about why each answer is right. Total: 16 marks.
Section A · Multiple choice 5 marks
1. Which of these is attracted to a magnet?
(A) A wooden ruler(B) A steel clip(C) A plastic cup(D) A rubber eraser
Answer: (B) A steel clipIron and steel are magnetic materials. Wood, plastic and rubber are not.
2. Which method makes a magnet by coiling wire around an iron nail?
(A) The electrical method(B) The stroke method(C) The hanging method(D) The pushing method
Answer: (A) The electrical methodIn the electrical method, the wire is coiled around an iron nail and connected to a battery to make an electromagnet.
3. Ali strokes a steel needle with one pole of a magnet. How should he stroke it to make a magnet?
(A) Back and forth with both poles(B) In different directions each time(C) With the magnet held still on the needle(D) In the same direction, using the same pole each time
Answer: (D) In the same direction, using the same pole each timeHe must use the same pole, stroke in the same direction, and lift the magnet to return to the start.
4. Mei coils wire around a nail and connects it to a battery. How can she make this electromagnet stronger?
(A) Use a shorter wire(B) Use a wooden nail(C) Add more turns of wire(D) Remove the battery
Answer: (C) Add more turns of wireMore turns of wire, or more batteries, make a stronger electromagnet.
5. Which of these uses an electromagnet?
(A) A compass(B) A crane lifting iron in a scrapyard(C) A fridge door(D) A doorstop
Answer: (B) A crane lifting iron in a scrapyardA scrapyard crane uses an electromagnet to lift iron and steel objects. It can be switched off to drop them.
Section B · Fill in the blanks 5 marks
6. Aluminium and copper are metals, but they are materials.
Answer: non-magneticNot all metals are magnetic. Only iron and steel are attracted to magnets.
7. The more times a steel nail is stroked, the the magnet it becomes.
Answer: strongerMore strokes make a stronger magnet.
8. We can measure how strong a magnet is by counting the number of steel it attracts.
Answer: clipsMore clips attracted means a stronger magnet.
9. A freely hanging magnet rests in the direction.
Answer: north-southA freely suspended magnet works like a compass.
10. In a fair test, we change variable only.
Answer: oneAll the other variables must stay the same.
Section C · Short answers 6 marks (2 each)
11. Name the two ways to make a magnet from a piece of steel or iron.
Answer: The stroke method (1 mark) and the electrical method (1 mark).Stroke it with a magnet, or use a battery and coiled wire to make an electromagnet.
12. Raj wants to find out if more turns of wire make a stronger electromagnet. What should he change, and what should he keep the same? Give one thing he should keep the same.
Answer: Change: the number of turns of wire (1 mark). Keep the same: the nail, or the number of batteries, or the type of clips (any one, 1 mark).This is a fair test. Only one variable is changed.
13. Why is an electromagnet useful for lifting iron in a scrapyard?
Answer: It can be switched on to lift the iron (1 mark) and switched off to let go of it (1 mark).An ordinary magnet cannot be turned off. An electromagnet only works when the current flows.
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