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Alicja Science - Year 8 > Magnetism > Flashcards

Magnetism Flashcards

1
Q

What 4 metals do magnets pick up?

A

Nickel, cobalt, iron, steel

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2
Q

Name metals that magnets won’t pick up

A

Copper, aluminium, gold, silver

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3
Q

How do you show that an object is a magnet?

A

If it is repelled by another magnet

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4
Q

The strongest parts of a magnet are

A

The poles, North and South

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5
Q

What are magnetic materials that are strongly attracted to magnets

A

Ferromagnetic/ nickel, cobalt, iron

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6
Q

How do you know when a food tin is made of steel?

A

To see if a magnet is attracted to it. Steel is a magnetic material - tin is not

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7
Q

Explain a fridge door arrangement.

A

The fridge frame and door are both metals that are attracted to the magnetic rubber in between, meaning that they stay shut together.

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8
Q

Explain how to make a magnet using a test tube of iron filings.

A
  • Shake the tube to mix the iron filings
  • Check the tube is not magnetised (both ends attract compass needle)
  • Stroke the tube in 1 direction, with one pole of a magnet. Watch the iron filings line up
  • Check that the tube is magnetised (one end should repel the compass needle)
  • Shake the tube to mix the fillings. Use the compass to check that the magnetism had gone
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9
Q

Does this iron filling experiment suggest that a magnet can be made from magnetic materials?

A

Yes

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10
Q

What is a magnet?

A

An object that possess the property of attracting certain substances (iron, nickel, cobalt)
A magnet has two poles called North and South

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11
Q

What is a magnetic material?

A

A magnetic material is a material that can be magnetised and is attracted to magnets

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12
Q

Name another way to magnetise a magnetic material.

A

Place a piece of iron by leaving it next to a magnet for a while. Eventually, the domains move around so they are lined up.

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13
Q

Name a few ways on how to remove magnetism

A

Don’t cut it up
• Use a hammer so the vibrations cause the atoms to move around and point in different directions.
• Drop the magnet (for the same reason as above)
• Heat the magnet (excessive heat gives the atoms energy and causes atoms to move rapidly. They knock neighbouring atoms out of alignment)

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14
Q

Domain?

A

A pair of atoms that have a North and South Pole

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15
Q

Why doesn’t a normal piece of iron act like a magnet?

A

Because iron is an element that has only one atom. But the domains are not lined up. A material needs to have two to have poles

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16
Q

What are the 3 stages of domains when being magnetised?

A

Unmagnetised, partially magnetised and fully magnetised

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17
Q

Why should you NOT drop magnets on the floor?

A

Because the vibrations will mix the domains and the magnet will de magnetise

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18
Q

How can you show a magnetic field using iron fillings?

A
  • Place two exercise books on the table and pit one magnet in the gap between them
  • put a plain sheet of paper over the magnet and rest it on the books
  • Shake the iron fillings onto the paper
  • Tao the corner of the paper with a pencil and keep tapping until you are happy with the pattern

If you want the pattern to be permanent use waxed paper and then melt the wax

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19
Q

How to show a magnetic field using a plotting compass

A
  • Place your magnet in the middle of a sheet of paper - turn the paper so the North end of the magnet is pointing north
  • Draw around the magnet and write an “N” where the North Pole of the magnet is.
  • Then draw a dot at the top right hand corner of the magnet
  • Place the compass there so that the needle points away from the dot
  • Next draw a dot on the paper at the other end of the needle
  • Move the compass to the next dot and do the same for 6 more dots then start at a new position near the magnet
20
Q

What is a magnetic field?

A

The area around a magnet where magnetic materials (eg iron) will experience a force

21
Q

Where will the north needle of a compass point and why?

A

South because opposites attract

22
Q

What materials will let magnetism act through

A

Paper, aluminium, wood etc

23
Q

What happens when magnetism can’t pass trough a material?

A

It will block the magnetic field and the paper clip will drop

24
Q

What are substances that let magnetism act through them

A

Substances that cannot be magnetised.

25
Q

How is a magnetically hard material different from a magnetically soft material?

A

A magnetically hard material retains it’s magnetism

26
Q

Are all metals magnetic materials

A

No, but metals are the only material that can be magnetic materials.

27
Q

Magnetic North is…

A

Geographical South

28
Q

When do compasses not work?

A

When it’s near a magnetic material.

29
Q

What is the best way to increase the strength of an electromagnet?

A

High voltage and current. More amount of coils. Using an iron core

30
Q

What are the dangers that might arise when using an electro-magnet?

A

The core may become extremely hot very quickly

31
Q

What is the difference between a magnet and a magnetic material?

A

Magnetic materials cannot create a magnetic field.

32
Q

Examples of use in magnetism:

A 
Recycling
Navigating- compasses 
Headphones
Computer hard-drives
Fridges
MRI - medical scanners
33
Q

What do you need to make an electromagnet?

A

Power supply
Coil of wire
Soft iron rod
Connecting wires

34
Q

What are the advantages and disadvantages of an electromagnet compared to a bar magnet?

A

You can increase the strength
You can turn it on and off

However an electromagnet needs a constant supply of power

35
Q

Why should soft iron cores be used in electromagnets instead of steel?

A

Because iron can be demagnetised and magnetised quickly whilst steel would stay magnetised after the current is switched off.

36
Q

Thumbs up…

A

Anti-clockwise

37
Q

Thumbs down

A

Clockwise

38
Q

What is an electromagnet?

A

A magnet that runs on electricity. It’s strength can be increased so is a good alternative for a permanent magnet when it comes to moving things.

39
Q

What is conventional current?

A

Current that flows from positive to negative

+ to -

40
Q

What is a long coil called?

A

A solanoid

41
Q

What does a current going through the wire cause…?

A

A magnetic field around the wire

42
Q

3 fingers represent

A

Thumb - M for motion
First finger - F for field
Second finger - C for current

43
Q

Label the parts of a relay circuit for an electric bell

A 
Cell
Switch
Electromagnet 
Gong
Armature
Contacts
Pivot
44
Q

Why do we use Flemings left hand grip rule?

A

To find out the direction of force

45
Q

Order how relay circuits work.

A
  • Switch is turned on
  • Current passes through the coil relay circuit (los current)
  • The magnetic field is produced in the coil
  • The pivoted armature is attracted to the coil
  • The contacts are pushed together
  • The Current passes through the motor circuit (High Current)
  • The starter motor operates to start the car
46
Q

What is a relay circuit?

A

A relay is an electrically operated switch. Many relays use an electromagnet to operate the switch.

47
Q

Electric bells…

A
  • The switch is turned on
  • A magnetic field is produced around the solenoid
  • The armature is attracted to the electromagnet and hits the gong
  • A gap between the contacts breaks the circuit
  • No current can flow so the magnetic field disappears
  • The armature is released back and the contacts touch again
  • The current flows again and the cycle repeats

Alicja Science - Year 8 (15 decks)

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