Primary 3 Science Magnets Quiz

Answer Key: Primary 3 Science Quiz - Magnets

Total Marks: 30

Section A: Multiple-Choice Questions (10 x 1 mark = 10 marks)

1. C. Iron

• Explanation: Iron is a magnetic material. Magnets attract objects made of iron and steel. Wood, plastic, and glass are not magnetic materials.
• Common Mistake: Students may think all metals are magnetic. Only some metals like iron, steel, nickel, and cobalt are magnetic. Copper and aluminium are not magnetic.

2. B. North-South

• Explanation: A freely suspended bar magnet acts like a compass. Its north pole points towards the Earth's geographic North Pole, and its south pole points towards the geographic South Pole. This is because the Earth itself acts like a giant magnet.
• Common Mistake: Students may think it points East-West or in a random direction.

3. B. They will repel each other.

• Explanation: Like poles (North-North or South-South) repel each other. Unlike poles (North-South) attract each other. Since both are north poles, they will push away from each other.
• Common Mistake: Students often confuse the rule and think all poles attract.

4. C. A steel paperclip

• Explanation: Steel is a magnetic material because it contains iron. Magnets attract objects made of iron or steel. Plastic, wood, and glass are non-magnetic materials.
• Common Mistake: Students may think a magnet attracts all shiny or metallic objects.

5. B. Poles

• Explanation: The two ends of a magnet are called its north pole and south pole. The magnetic force is strongest at the poles.
• Common Mistake: Students may use general terms like "ends" or "sides" instead of the specific scientific term "poles."

6. C. Cutting a piece of paper

• Explanation: Magnets are used to hold things (like notes on a fridge), close cupboard doors (magnetic catches), and pick up magnetic materials (like iron filings). A magnet cannot cut paper; scissors or a blade is needed for that.
• Common Mistake: Students may not think of everyday uses of magnets.

7. B. Magnetism

• Explanation: Magnetism is the invisible force that a magnet exerts. It can attract or repel other magnets and attract magnetic materials.
• Common Mistake: Students may confuse magnetism with gravity or friction.

8. B. Through a distance

• Explanation: A magnet can attract a magnetic object without touching it. This shows that magnetic force can act at a distance. The force is strongest when the object is close to the magnet.
• Common Mistake: Students may think a magnet must touch an object to attract it.

9. C. Steel

• Explanation: Steel is a magnetic material. It can be magnetised by methods like stroking or using electricity. Copper, aluminium, and rubber are not magnetic and cannot be made into magnets.
• Common Mistake: Students may think any metal can be magnetised.

10. A. North pole

• Explanation: Unlike poles attract. Since the south pole of magnet X is attracted to one end of magnet Y, that end must be the north pole (South attracts North).
• Common Mistake: Students may think like poles attract.

Section B: Fill in the Blanks (5 x 2 marks = 10 marks)

11. south

• Explanation: A magnet has two poles: the north pole and the south pole.
• Marking: 1 mark for the correct word.

12. attract and repel

• Explanation: Unlike poles (north and south) attract each other. Like poles (north-north or south-south) repel each other.
• Marking: 1 mark for each correct word (2 marks total).

13. north-south

• Explanation: A freely suspended bar magnet will always align itself in the north-south direction. This is how a compass works.
• Marking: 1 mark for the correct direction. Accept "north and south" or "north-south."

14. magnetic

• Explanation: Materials that are attracted to a magnet are called magnetic materials. Examples include iron and steel.
• Marking: 1 mark for the correct word.

15. stroking

• Explanation: The stroking method is one way to make a magnet. You stroke a steel bar with one pole of a magnet in one direction repeatedly.
• Marking: 1 mark for the correct word.

Section C: Short-Answer Questions (5 x 2 marks = 10 marks)

16. Answer: The metal paperclip will be attracted to the magnet. The plastic toy car will not be attracted. Explanation: The metal paperclip is likely made of steel, which is a magnetic material. Plastic is a non-magnetic material, so it will not be attracted to a magnet. Marking:

• 1 mark for correctly identifying the paperclip.
• 1 mark for explaining that it is made of a magnetic material (steel/iron).

17. Answer: The two magnets will attract each other. Explanation: The north pole of Magnet A is facing the south pole of Magnet B. Unlike poles attract each other. Marking:

• 1 mark for stating "attract."
• 1 mark for explaining that unlike poles (north and south) attract.

18. Answer: (Accept any reasonable example, such as:)

• Using a magnet to hold notes on a refrigerator door.
• Using a magnetic catch to keep a cupboard door closed.
• Using a compass (which has a magnetic needle) to find directions.
• Using a magnet to pick up iron filings or spilled paperclips. Marking:
• 1 mark for a clear example of a magnet being used.
• 1 mark for stating where it is used (classroom or home). Accept a general example without specifying location.

19. Answer: The iron nail and the steel paperclip. Explanation: Iron and steel are magnetic materials. Copper and plastic are not magnetic. Marking:

• 1 mark for each correct object (2 marks total). Must name both objects correctly.

20. Answer: (Accept any one correct step, such as:)

• Stroke the steel needle with one pole of the bar magnet in one direction repeatedly (e.g., 50 times).
• OR: Rub the magnet along the needle from one end to the other, always in the same direction.
• OR: Place the needle in a coil of wire connected to a battery (electrical method). Explanation: The stroking method aligns the magnetic domains in the steel needle, turning it into a temporary magnet. Marking:
• 1 mark for describing a correct method (stroking or electrical).
• 1 mark for including a key detail (e.g., "in one direction," "repeatedly," or "using a battery").
• Accept any reasonable description of a valid method.

End of Answer Key