Pupil sheet · Magnets and magnetic fields
Magnetic materials — questions
Name ______________________ Date ____________
Try every question before you use a nudge. Write in full sentences where you are asked to explain.
1. identify
A pupil holds a magnet against each object on a tray. Which objects does the magnet attract? Choose all that are correct.
Tick every correct statement.
- A brass key
- A steel paper clip
- An aluminium drinks can
- A plastic comb
- A copper pipe
- An iron washer
- A strip of nickel
Nudge (only if you are stuck): Only four materials you need to know are magnetic. Which of them are on the tray?
2. state / explain
A pupil says: “Copper conducts electricity very well, so it must be a magnetic material.” (a) State the difference between a magnetic material and a non-magnetic material. (b) Explain why the pupil is wrong, and identify one metal that is a magnetic material.
(a) The difference
(b) Why the pupil is wrong
Nudge (only if you are stuck): What does a magnet do to a copper pipe? Is conducting electricity the same property as being magnetic?
3. identify
A pupil tests three metal bars, J, K and L, by bringing each end of each bar near the S pole of a magnet. One end of J is attracted and its other end is repelled. Neither end of K moves. Both ends of L are attracted. Which row of the table is correct?
| Row | Bar J | Bar K | Bar L |
|---|---|---|---|
| A | unmagnetised magnetic material | non-magnetic | magnet |
| B | magnet | non-magnetic | unmagnetised magnetic material |
| C | magnet | unmagnetised magnetic material | non-magnetic |
| D | non-magnetic | magnet | unmagnetised magnetic material |
Circle one answer.
- A
- B
- C
- D
Nudge (only if you are stuck): Which result can only happen between two magnets?
4. explain / describe
A pupil holds the same end of a steel bar near the N pole of a magnet and then near its S pole. Both times the end is attracted. She concludes: “The bar is a magnet.” (a) Explain why her conclusion is wrong. (b) Describe a test that would show whether a bar is a magnet.
(a) Why the conclusion is wrong
(b) A test for a magnet
Nudge (only if you are stuck): If that end of the bar were a pole, what would one of the magnet’s poles do to it?
5. identify
The S pole of a bar magnet holds an iron nail by its head, with the nail hanging below it. A paper clip hangs from the point of the nail. Match each end to the pole induced in it.
Write the number of the matching option.
- S pole
- N pole
- The head of the nail: ______
- The point of the nail: ______
- The top of the paper clip: ______
- The bottom of the paper clip: ______
Nudge (only if you are stuck): Start at the magnet: the end nearest a pole becomes the opposite pole. Then work down the chain.
6. explain
A steel paper clip lies on a table. A pupil brings the N pole of a magnet near one end of it, and the clip slides towards the magnet. She turns the magnet round and brings its S pole near the same end, and the clip slides towards it again. Explain both results, using the idea of induced magnetism.
With the N pole near
With the S pole near
Nudge (only if you are stuck): What does the clip become while it is in the magnet’s field, and which pole forms at its near end each time?
7. identify
Which row of the table compares soft iron and steel correctly?
| Row | Soft iron is magnetised | When the magnet is removed, soft iron | Steel is used to make |
|---|---|---|---|
| A | less easily than steel | keeps its magnetism | electromagnet cores |
| B | easily | keeps its magnetism | permanent magnets |
| C | less easily than steel | loses most of its magnetism | electromagnet cores |
| D | easily | loses most of its magnetism | permanent magnets |
Circle one answer.
- A
- B
- C
- D
Nudge (only if you are stuck): Think of the clips on the two rods: which rod dropped its clips when the magnet was lifted away?
8. calculate / identify
Two rods of the same size, X and Y, are touched against identical magnets and dipped into paper clips. While touching its magnet, X holds 12 clips and Y holds 15 clips. When the magnets are removed, X still holds 9 clips and Y holds 1 clip. (a) Calculate the percentage of its clips that each rod keeps. Give each answer to 2 significant figures. (b) Identify which rod is soft iron, and give the reason.
(a) Rod X keeps: ______________ unit ________
(a) Rod Y keeps: ______________ unit ________
(b) Which rod is soft iron, and why
Nudge (only if you are stuck): Percentage kept = clips kept ÷ clips held at first × 100.
9. identify
Which use needs an electromagnet rather than a permanent magnet?
Circle one answer.
- A magnet that holds a note on a fridge door
- A magnet that holds a phone in a holder on a car’s dashboard
- A lifting magnet that must drop each steel plate when it is in place
- The needle of a plotting compass
Nudge (only if you are stuck): Which job needs the magnet to let go when a switch is flicked?
10. identify / explain
Match each use to the kind of magnet it needs.
Write the number of the matching option.
- Electromagnet
- Permanent magnet
- A magnetic knife rack on a kitchen wall: ______
- A lifting magnet that picks up one steel plate at a time and puts it down on a lorry: ______
- An electric bell, whose hammer is pulled and let go many times a second: ______
- A magnet that holds a poster on a steel noticeboard: ______
- The needle of a plotting compass: ______
Nudge (only if you are stuck): For each use, ask: must the magnet let go, or switch on and off, when a current is switched?
11. suggest / explain
A coin looks as if it is made of copper, but a magnet picks it up. (a) Suggest why. (b) A pupil says this shows that the coin is a magnet. Explain whether she is right.
(a) Why the magnet picks it up
(b) Is the coin a magnet?
Nudge (only if you are stuck): Is copper a magnetic material? What could be under a thin copper surface?
12. describe
A technician has two rods that look the same. One is soft iron and one is steel. Using one bar magnet and a box of paper clips, describe an experiment to find out which rod is which. Include how to make the test fair and the result that identifies each rod.
Method
Making it fair
The result for each rod
Nudge (only if you are stuck): Test two things: how many clips each rod picks up while touching the magnet, and how many it keeps afterwards.
13. explain / suggest
In a school corridor, a heavy fire door is held open by an electromagnet on the wall, which holds a steel plate on the door. When the fire alarm sounds, the current in the electromagnet is switched off and the door swings shut. (a) Explain why the door is released when the current is switched off. (b) Explain why the core of the electromagnet is soft iron and not steel. (c) Suggest one advantage of using an electromagnet here rather than a permanent magnet.
(a) Why the door is released
(b) Why soft iron
(c) One advantage
Nudge (only if you are stuck): What happens to a soft-iron core, and to a steel one, when the current stops?