Cambridge Secondary (7-9). Stage 8. MCE Science. Workbook - Unit 11: Magnetism

Magnetise a pin or needle by stroking a bar magnet along it in one direction, lifting the magnet before returning; repeat 50 times. Draw and cut out a wax-paper circle smaller than a bowl, mark N, E, S and W, and thread the needle through it in the N–S direction. Float the paper and needle on water. Work under adult supervision because the needle and scissors are sharp. What do the needle and paper do?

Magnetise a pin or needle by stroking a bar magnet along it in one direction, lifting the magnet before returning; repeat 50 times. Draw and cut out a wax-paper circle smaller than a bowl, mark N, E, S and W, and thread the needle through it in the N–S direction. Float the paper and needle on water. Work under adult supervision because the needle and scissors are sharp. Why did the needle move the way it did in question 6 (your observation of the floating needle and paper)?

Magnetise a pin or needle by stroking a bar magnet along it in one direction, lifting the magnet before returning; repeat 50 times. Draw and cut out a wax-paper circle smaller than a bowl, mark N, E, S and W, and thread the needle through it in the N–S direction. Float the paper and needle on water. Work under adult supervision because the needle and scissors are sharp. How does this prove that the Earth’s core acts like a giant magnet?

Make an electromagnet with insulated copper wire wrapped tightly around an iron nail, leaving a few centimetres free at each end and stripping the insulation from both ends. Connect the wire ends to the two terminals of a 9 V cell; an optional switch can turn the circuit on and off. Disconnect promptly after each test: the wire can get hot. Once the circuit is connected, your electromagnet should be ready to use. Test it by bringing it close to some small metal objects. What happens?

Make an electromagnet with insulated copper wire wrapped tightly around an iron nail, leaving a few centimetres free at each end and stripping the insulation from both ends. Connect the wire ends to the two terminals of a 9 V cell; an optional switch can turn the circuit on and off. Disconnect promptly after each test: the wire can get hot. How could you improve on the design of your electromagnet?

What concepts are you unsure of? What would you like to know more about in this chapter? Write them down.

Describe how you would use a piece of paper and iron filings to find the magnetic field around a bar magnet.

Use 1 to 5 to number the steps to show how an MRI machine scans and creates a detailed image of the inside of the body.

□ When the radio waves are turned off, the hydrogen atoms return to their original alignment, releasing energy.

□ The strong magnetic field aligns the hydrogen atoms in the body.

□ The MRI machine sends radio waves into the body, and the hydrogen atoms absorb them.

□ The MRI machine detects the released energy and uses it to create a detailed image of the inside of the body.

□ The patient lies down on a bed and is placed into the centre of a large circular magnet.

Peter sprinkled some iron filings on a piece of paper placed over two magnets. He observed the following patterns on the paper.



What does the pattern represent?

Peter sprinkled some iron filings on a piece of paper placed over two magnets. He observed the following patterns on the paper.



Tick (✓) the correct box about the magnets used in Peter’s set-up: □ like poles □ unlike poles.

Peter sprinkled some iron filings on a piece of paper placed over two magnets. He observed the following patterns on the paper.



Tick (✓) the correct box about the magnets used in Peter’s set-up: □ attractive force □ repulsive force.

Describe how you can use a compass to show that Earth has a magnetic field. You may draw a diagram with labels to help you explain.

Aisha makes an electromagnet like the one shown in the diagram. She uses the electromagnet to pick up paper clips. Aisha predicts that if she adds more cells, the strength of the electromagnet will increase. She does an experiment to test her prediction. The table shows her results.



| Number of cells | Number of paper clips attracted |
|---|---|
| 1 | 5 |
| 2 | 7 |
| 3 | 9 |
| 4 | 10 |
| 5 | 11 |

Is her prediction correct? Explain your answer.

Aisha makes an electromagnet like the one shown in the diagram. She uses the electromagnet to pick up paper clips. Aisha predicts that if she adds more cells, the strength of the electromagnet will increase. She does an experiment to test her prediction. The table shows her results.



| Number of cells | Number of paper clips attracted |
|---|---|
| 1 | 5 |
| 2 | 7 |
| 3 | 9 |
| 4 | 10 |
| 5 | 11 |

Plot her results on the grid below.

Aisha makes an electromagnet like the one shown in the diagram. She uses the electromagnet to pick up paper clips. Aisha predicts that if she adds more cells, the strength of the electromagnet will increase. She does an experiment to test her prediction. The table shows her results.



| Number of cells | Number of paper clips attracted |
|---|---|
| 1 | 5 |
| 2 | 7 |
| 3 | 9 |
| 4 | 10 |
| 5 | 11 |

How could Aisha improve her investigation?

Aisha makes an electromagnet like the one shown in the diagram. She uses the electromagnet to pick up paper clips. Aisha predicts that if she adds more cells, the strength of the electromagnet will increase. She does an experiment to test her prediction. The table shows her results.



| Number of cells | Number of paper clips attracted |
|---|---|
| 1 | 5 |
| 2 | 7 |
| 3 | 9 |
| 4 | 10 |
| 5 | 11 |

How else could she increase the strength of the electromagnet?

Aisha makes an electromagnet like the one shown in the diagram. She uses the electromagnet to pick up paper clips. Aisha predicts that if she adds more cells, the strength of the electromagnet will increase. She does an experiment to test her prediction. The table shows her results.



| Number of cells | Number of paper clips attracted |
|---|---|
| 1 | 5 |
| 2 | 7 |
| 3 | 9 |
| 4 | 10 |
| 5 | 11 |

If Aisha used eight cells, how many paper clips would have been attracted? Explain your answer.

Give two examples of industrial uses of electromagnets. Briefly describe how the electromagnets work.