Primary 3 Science · Answers and explanations
Properties of Magnets Investigation
Use this page to check the worksheet together. Talk about why each answer is right. Total: 20 marks.
Section A · Multiple choice 8 marks
1. Table 1 shows the results of testing four objects with a magnet. Which object is most likely made of steel?1 mark
Table 1| Object | Attracted to a magnet? |
|---|
| P | Yes |
| Q | No |
| R | No |
| S | No |
(A) Q(B) P(C) R(D) S
Answer: (B) POnly object P is attracted to the magnet. Steel and iron are the magnetic materials.
2. Table 2 shows how many paper clips stuck to different places on a bar magnet. Where is the magnet weakest?1 mark
Table 2| Position on the bar magnet | A (left end) | B | C (centre) | D (right end) |
|---|
| Paper clips that stick | 11 | 3 | 1 | 10 |
(A) C (centre)(B) A (left end)(C) B(D) D (right end)
Answer: (A) C (centre)Only 1 clip stuck at C. The fewest clips means the weakest pull.
3. Look at Table 2 again. Which two positions have the strongest pull?1 mark
Table 2| Position on the bar magnet | A (left end) | B | C (centre) | D (right end) |
|---|
| Paper clips that stick | 11 | 3 | 1 | 10 |
(A) B and C(B) A and C(C) C and D(D) A and D
Answer: (D) A and DA and D are the two ends (poles) of the magnet. The pull is strongest at the poles.
4. Two ring magnets are put on a pencil. The top ring floats above the bottom ring, as shown. What does this show?1 mark
(A) The two facing sides are unlike poles and they attract(B) The rings are made of plastic(C) The two facing sides are like poles and they repel(D) The bottom ring is not a magnet
Answer: (C) The two facing sides are like poles and they repelFloating means the top ring is being pushed up. Only like poles repel, so the facing sides are like poles.
5. A steel rod is attracted to both ends of a bar magnet. Can we say the rod is a magnet?1 mark
(A) Yes, because it is attracted(B) No, it may only be a magnetic material(C) Yes, because it is made of metal(D) No, because steel is not magnetic
Answer: (B) No, it may only be a magnetic materialA magnetic material is attracted by both poles. Only repulsion proves an object is a magnet.
6. Object X is attracted to the north pole of a magnet but repelled by the south pole. What is object X?1 mark
(A) A magnet(B) A piece of iron(C) A piece of plastic(D) A piece of wood
Answer: (A) A magnetOnly a magnet can repel another magnet. A piece of iron would be attracted by both poles.
7. Ben turns a freely hanging bar magnet around and waits. Which direction does its south pole point to when it stops?1 mark
(A) North(B) East(C) West(D) South
Answer: (D) SouthA freely hanging magnet rests in the north-south direction. The N pole points north and the S pole points south.
8. Which of these is NOT a magnetic material?1 mark
(A) An iron nail(B) A steel paper clip(C) A copper wire(D) A steel screw
Answer: (C) A copper wireCopper is a metal but it is not magnetic. Iron and steel are magnetic.
Section B · Show what you know 12 marks
9. Use Table 2. How many more paper clips stuck at A than at C?2 marks
Table 2| Position on the bar magnet | A (left end) | B | C (centre) | D (right end) |
|---|
| Paper clips that stick | 11 | 3 | 1 | 10 |
Answer: 10 more clips (1 mark for 11 and 1, 1 mark for the answer 10).11 − 1 = 10.
10. Why must we test a mystery object with both poles of a magnet before we say it is a magnet?2 marks
Answer: Because a magnetic material is attracted by both poles (1 mark). Only a magnet is repelled by one of the poles (1 mark).Attraction alone does not prove it is a magnet.
11. The south pole of Magnet 1 attracts Magnet 2. Which pole of Magnet 2 is facing the south pole of Magnet 1? Give a reason.2 marks
Answer: The north pole (1 mark). Unlike poles attract (1 mark).S and N attract. S and S would repel.
12. Sam wants to find out which of two magnets is stronger by counting the paper clips each one picks up. Give one thing he must keep the same to make it a fair test.2 marks
Answer: Any one of: the size or type of the paper clips, the number of clips in the pile, the way he dips the magnet, how long he holds it (1 mark for naming one variable that is kept the same, 1 mark for a clear reason or a sentence saying the test is fair; 0 marks for naming the magnet as the thing kept the same).Only the magnet should change.
13. Dev says, "An aluminium can is attracted to a magnet because it is made of metal." Is Dev correct? Explain.2 marks
Answer: No (1 mark). Aluminium is a metal but it is not a magnetic material, only iron and steel are (1 mark).Not all metals are magnetic.
14. Table 3 shows the results of three trials with a hanging bar magnet. What do you expect to see in Trial 4? Explain.2 marks
Table 3| Trial | Which way did the N pole point? |
|---|
| 1 | North |
| 2 | North |
| 3 | North |
Answer: The N pole will point north again (1 mark). A freely hanging magnet always comes to rest in the north-south direction (1 mark).The results repeat each time.
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