Magnets and magnetic fieldsIB MYP Sciences: Subtopic test

1. 1
   A student in Johannesburg tests four objects with a bar magnet: an iron nail, a copper coin, a steel paper clip and a plastic ruler.

   (a)

   Which objects will be attracted to the magnet?

   [1 mark]

   • AThe iron nail and the steel paper clip
   • BThe copper coin and the plastic ruler
   • CThe iron nail and the copper coin
   • DAll four objects

   (b)

   The student then brings the north pole of one bar magnet close to the north pole of a second bar magnet. What happens?

   [1 mark]

   • AThe magnets attract each other
   • BThere is no force between them
   • CThe magnets lose their magnetism
   • DThe magnets repel each other

   (c)

   Explain why the iron nail is attracted to the magnet but the copper coin is not.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A compass contains a small magnetised needle that is free to turn. A hiker in Switzerland uses one to find north on a mountain path, and a science class uses one to investigate the field around a bar magnet.

   (a)

   Why does the needle of a compass turn to point towards the north?

   [1 mark]

   • AThe needle is attracted to the Sun
   • BThe needle is a small magnet that lines up with the Earth's magnetic field
   • CThe needle is pulled north by gravity
   • DThe needle is attracted to the ice in the Arctic

   (b)

   Which statement about the magnetic field lines around a bar magnet is correct?

   [1 mark]

   • AOutside the magnet they point from south to north
   • BThey cross each other where the field is strongest
   • CThey point from the north pole to the south pole, and are closest together where the field is strongest
   • DThey are furthest apart near the poles

   (c)

   Describe how the class could use a compass to plot the magnetic field line around a bar magnet.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A technician at a recycling centre in Singapore separates mixed metal waste with a large magnet. Back in the school laboratory, a science class uses small bar magnets and iron nails to model the same effect.

   (a)

   Explain how the magnet separates iron and steel scrap from aluminium, copper and plastic.

   [3 marks]

   (b)

   A student holds the north pole of a bar magnet near one end of an iron nail, and the nail picks up some iron pins. Explain why the pins are picked up and state what happens when the magnet is taken away.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A student in Ottawa is investigating how a bar magnet affects a compass, because the mountain rescue team she volunteers with relies on magnetic compasses as well as GPS devices to navigate.

   (a)

   Design an investigation to find how the distance from a bar magnet affects a compass needle. Include a testable hypothesis.

   [6 marks]

   (b)

   Discuss the benefits and drawbacks of mountain rescue teams navigating with magnetic compasses rather than GPS devices, and reach a justified conclusion.

   [6 marks]

   Total for question 4: 12 marks

End of questions