8J SATsQuestions Booklet

Unit 8J (Magnets and electromagnets)

Question No.

Level Mark

1(01) 3 4

2(05) 3 6

3(99) 4 4

4(97) 4 5

5(05) 4 5

6(05) 6 6

7(95) 6 5

8(97) 7 6

9(99) 7 5

10(05) 7 5

11(01) 7 6

12(01) 8 7

13(97) 8 3

Rainford High Technology College 1


1. Ali made a cat-flap to fit into a door.

door

cat-flap

bottom of door

(a) (i) On the diagram above, draw an arrow to show the direction of the force of the cat’s head on the cat-flap.

1 mark

(ii) Add a label to the diagram to show the pivot of the cat-flap.Label it P.

1 mark

When the cat has gone through the cat-flap, the weight of the cat-flap makes the flap close.

NS

door

cat-flap

m agne ts

bo ttom o f door

(b) Ali used two bar magnets to keep the cat-flap closed, so that it does not blow open in the wind.

On the diagram above, label both the North and South poles on the magnet in the cat-flap.

1 mark(c) Friction at the pivot made the cat-flap squeak. What could Ali put on the pivot to

make the friction less?

…………………………………

1 mark

Maximum 4 marks

2. Jenny dropped her torch down a drain.Rainford High Technology College 2

Unit 8J (Magnets and electromagnets)The torch was still switched on but Jenny could not see it.

not to scale

(a) (i) Jenny lowered a mirror into the drain and placed it at position P.

At which angle should Jenny put the mirror to see the torch?Tick the correct box.

1 mark

(ii) What happens to the light from the torch when it hits the mirror?

......................................................................................................................

1 mark

(b) The diagrams below show the symbols for three parts of the torch circuit.

(i) On the line below each diagram, give the name of the part.

........................................ ........................................ .........................................

3 marks

(ii) In the space below, draw a circuit diagram to show how these threeparts are connected in a torch.

1 mark

maximum 6 marks


Unit 8J (Magnets and electromagnets)3. Rachel has a small block of metal. She wants to know if it is a magnet.

R achel'sblock o f m eta l

bar m agne t

N S

She holds the North pole of the bar magnet near one end of the block of metal. They attract. Then she holds the South pole of the bar magnet near the same end of the block of metal. Again they attract.

(a) Explain how this shows that Rachel’s block of metal is not a permanent magnet.

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..........................................................................................................................

1 mark

(b) What metal could Rachel’s block be made from?

………………………………………………………………………………………

1 mark

(c) Rachel puts the block of metal in a thin plastic bag.What effect, if any, will the bar magnet now have on the block?

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1 mark

(d) Rachel puts the bar magnet into a pile of coins. Some of the coins are attracted to the magnet but some are not.Suggest a reason for this.

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1 mark

Maximum 4 marks


Unit 8J (Magnets and electromagnets)4. (a) The diagram shows two bar magnets.

m agnet A m agnet B

S

N

The north pole and south pole are shown on magnet A. The poles are not shown on magnet B.

Describe an experiment you could do, using magnet A, to find which end of magnet B is the north pole and which is the south pole.

Put the north pole of magnet A to an unknown pole of magnet B.If the poles attract, the known pole is S. If they repel the unknown pole is N.

3 marks

(b) The diagram shows a wooden truck near a wall. There is a strong magnet fixed to the wall and a strong magnet fixed to the front of the wooden truck.

w ooden truck

m agnetfixed totruck

m agne tfixed tow all

w all

S N N S

tab le

James holds the wooden truck so that it does not move.Then he lets go of the wooden truck. In which direction will it move?

.The truck will not move towards the wall, because the poles will repel.

1 mark

(c) James removes the magnet from the wooden truck. He gives the truck a push so that it rolls along the table.

What effect will friction have on the speed of the truck as it rolls along?

Friction will stop the truck.

1 mark

Maximum 5 marks

5. The drawing shows a toy shark. Magnets X and Y make the shark ‘float’above the plastic base.



(a) On magnet X, write the letters N and S to label the poles of the magnet.

1 mark

(b) (i) Choose a word from the list below to complete the sentence.

attract cancel repel

The toy shark ‘floats’ because the magnets repel each other.

1 mark

(ii) Sophie pressed down on the tail of the shark with her finger.

What happened to the shark when she removed her finger?

If she presses down the shark, the shark goes down. When she releases her finger, the shark floats.

1 mark


Unit 8J (Magnets and electromagnets)Sophie added weights to the toy shark and measured the distance between the two magnets.Her results are shown below.

weight added to the toy shark (N)

distance between the magnets (mm)

0.1 6

0.2 4

0.3 3

Complete the sentence below.

As the weight on the toy shark increased, the distance between the magnets

decreased.

1 mark

(d) Sophie turned the magnet in the plastic base the other way up.

What happened to the shark?

The magnets attract and the shark fall down.

1 mark

maximum 5 marks


Unit 8J (Magnets and electromagnets)6. Alex makes an electromagnet.

She winds insulated wire around an iron nail.She connects the wire to a power supply.She uses the electromagnet to pick up some steel paper-clips.

This is her prediction.

The more turns of wire around the iron nail the strongerthe electromagnet becomes.

(a) (i) Give the one factor she should change as she investigates her prediction.

The turns of the coil of wire

1 mark

(ii) Give one factor she should keep the same.

The power of supply

1 mark

(iii) Describe how she could use the paper-clips to measure thestrength of the electromagnet.

More iron nails picked up, the stronger the electromagnet.

1 mark


Unit 8J (Magnets and electromagnets)(b) Alex wrote a report of her investigation.

What would an odd result suggest?

Odd result will contradict her prediction. But her prediction was true with the experiment. Number of coils increases the strength of the electromagnet.

1 mark

(c) (i) Which size paper-clips would Alex use to make her results moreaccurate?Tick the correct box.

1 mark(ii) Give a reason for your choice.

The smaller the paper clips, the more accurate the results will be.

1 mark

maximum 6 marks

7. The diagram shows an electromagnet used in a door lock.

pushsw itch

iron corefixed todoor fram e

co il

spring

iron bolt

doordoorfram e


Unit 8J (Magnets and electromagnets)(a) The push switch is closed and the door unlocks. Explain in detail how this happens.

The current passes through the iron core and goes through the coil of wire. The current will push the spring forward and open the iron bolt. The door lock is opened.

3 marks

(b) The switch is released and the door locks. Explain in detail how this happens.

The switch is released. There is no current passing through. The spring rebounds and the door is locked.

2 marks

Maximum 5 marks

8. A pupil fixes a small electromagnet close to a thin springy steel sheet. The device acts like a small speaker. She connects a battery and switch to the electromagnet as shown.

electrom agne t

thinspringystee lsheet

case

(a) (i) When the pupil closes the switch, what will happen to the steel sheet?

The steel sheet will attract to the iron electromagnet.

1 mark

(ii) The pupil opens the switch again. What will happen to the steel sheet now?

The steel sheet will not be attracted to the electromagnet. ..........................................................................................................

1 mark

(iii) If the pupil had connected the battery the other way round, what difference would this have made to your answer to part (i)?

The way will be the other way around.

1 mark



The pupil removes the battery and switch. She connects the electromagnet to a power supply which switches the current on and off 1000 times each second. The steel sheet vibrates and makes a sound.

stee l shee tv ib ra tes andm akes a soundpow er supp ly

sw itches cu rren ton and o ff1000 tim eseach second

(i) She then adjusts the power supply so that the current is switched on and off 3000 times each second.

What difference does this make to the pitch of the sound?

Give a reason for your answer.

The more times you adjust the power supply, the pitch becomes higher.

2 marks

(ii) The pupil now adjusts the power supply so that the current is larger. Explain why this makes the sound louder.

A larger sound has bigger amplitude. A sound with bigger amplitude has a louder sound.

1 mark

Maximum 6 marks



9. The diagram shows a rectangular coil and circuit. It has two iron rods in it. The rods are parallel and touching. They are free to move.

(a) When the switch is closed, the two rods move apart.

(i) Explain why this happens.

When there is no current flowing through the electromagnet the rods have no strength to attract. Instead, they repel.

2 marks

(ii) The switch is then opened to break the circuit. What, if anything, happens to the two iron rods?

The two iron rods will be electric. If you touch them, you will get an electric shock.

1 mark

(b) One of the two iron rods is taken out and replaced with a brass rod. The rods are parallel and touching.What, if anything, will happen to the rods when the switch is closed?Explain your answer.

The rods will repel. Brass is not magnetic and there is still no current passing through.

2 marks

Maximum 5 marks

10. A reed switch is made of two iron strips inside a glass tube.The iron strips close together when a magnet is brought near.They spring apart again when the magnet is removed.


Unit 8J (Magnets and electromagnets)(a) Hilary set up the circuit shown below.

She tried to close the reed switch using an electromagnet.

She closed switch E but the electromagnet was not strong enough to close the reed switch.

(i) Give two ways Hilary could increase the strength of the electromagnet.

1 Increase the number of coils.

2 Use a magnetic material for the core.

2 marks

Hilary increased the strength of the electromagnet.The reed switch closed.The iron strips were magnetized as shown below.

She reversed the current in the coil of the electromagnet.On the diagram below, label the poles of the iron strips when thecurrent was reversed.



1 mark

(b) (i) Iron and steel are both magnetic materials.Explain why the strips must be made of iron and not steel.

Iron is more magnetic than steel. Steel contains other materials including iron. Iron acts like a permanent magnet.

1 mark

(ii) She replaced the reed switch with a piece of copper wire.The current through the bulb increased.

Explain why more current flowed through the bulb when the reed switch was replaced with copper wire.

Copper is good conductor of electricity and it is flexible to stretch to a long distance

1 mark

maximum 5 marks

11.(a) A pupil makes a small coil of copper wire and passes an electric current through it. The pupil places a small magnet near the coil.

coil N S m agnet

The magnet is attracted towards the coil. The pupil turns the magnet around so that the South Pole is nearest the coil.What effect, if any, will this have?

The South Pole will be attracted towards the coil.

1 mark



The pupil uses the coil and the magnet to make a simple ammeter to measure the current through a bulb.

coil

m agne t

p ivo t

straw paper c lip

scale

not to scale

(i) The paper clip is used to balance the weight of the magnet.Why the paper clip is further away from the pivot than the magnet is?


Unit 8J (Magnets and electromagnets)Paper clip can be attracted, by the magnet.

1 mark

(ii) Explain how a current in the coil makes the straw pointer move.

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

2 marks

(iii) The pupil places a piece of soft iron in the middle of the coil.Describe and explain how this will affect the reading on the scale when the same current flows through the coil.

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

…………………………………………………………………………………

2 marks

Maximum 6 marks

12. Anita has arranged a horseshoe magnet with a long bar magnet pivoted above it.

N

N

S

S

pivot

bar m agnet

horseshoem agnet

(a) Whenever Anita tips the bar magnet, it always moves back to the position shown in the diagram. Explain why this happens.

……….………………………………………………………………………………

……….………………………………………………………………………………

……….………………………………………………………………………………

……….………………………………………………………………………………

2 marks



(b) When a current is passed through a coil, it produces magnetic poles as shown in the diagram below.

N

S

Anita winds a coil around each end of the horseshoe magnet as shown below.

N

N

S

S

pivot

bar m agnet

horseshoem agnet

(i) Describe what will happen to the bar magnet when she closes the switch.Explain your answer.

…………………………………………………………………………………


Unit 8J (Magnets and electromagnets)…………………………………………………………………………………

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3 marks

(ii) Anita reverses the battery. Suggest what happens to the bar magnet.

…………………………………………………………………………………

…………………………………………………………………………………

1 mark

(iii) Anita replaces the battery with a power supply which changes the direction of the current every second. Suggest what happens to the bar magnet.

…………………………………………………………………………………

…………………………………………………………………………………

1 mark

Maximum 7 marks

13. Digital information can be stored on magnetic recording tape in several different ways. One way is shown in the diagram below.

m agnetisedarea of tape

record inghead

coil

tape

The recording head produces a magnetic field. The magnetic particles in the section of tape under the recording head line up with the field.

(a) As the tape moves past the recording head, different sections of the tape become magnetised. The direction of the current is changed at regular intervals.

How would the pattern on the tape be different if the tape were moved past the recording head more quickly?

....................................................................................................................

....................................................................................................................

1 mark


Unit 8J (Magnets and electromagnets)(b) The direction of the current is changed at regular intervals. The tape is

moved past the recording head at a steady speed.

The gap between the poles of the recording head is made much bigger. Suggest two effects this might have on the pattern on the tape.

1 ................................................................................................................

................................................................................................................

2 ................................................................................................................

................................................................................................................

2 marks

Maximum 3 marks


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8J SATsQuestions Booklet