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Physics year nine > Magnetism > Flashcards

Magnetism Flashcards

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1
Q

What is magnetism?

A

Magnetism: a force that magnets produce. It can cause two objects to attract or repel.

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2
Q

List the 4 materials that are magnetic.

A
  • Iron
  • nickel
  • cobalt
  • steel

Steel is an alloy of iron and carbon. The rest are raw materials.

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3
Q

Where were magnets discovered?

A

Magnesia - an area of ancient Greece.

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4
Q

What type of rock was were the first natural magnets discovered in?

A

Lodestone

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5
Q

What mineral is in loadstone that makes it magnetic?

A

Magnetite - Fe3O4

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6
Q

What will magnets not attract?

A

Anything that is non-magnetic.

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7
Q

What is a magnetic field?

A

The area around a magnet where magnetic materials experience a force.

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8
Q

How can a magnetic field be located?

A
  • plotting compass - show direction of the field
  • Iron filings - show shape of the field
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9
Q

What are the three rules of magnetic fields?

A
  1. Magnetic field lines can never cross.
  2. Magnetic field lines always go from the north pole to the south pole
  3. The spacing of the lines shows the strength of the magnetic field at that point. The closer the lines, the stronger the field
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10
Q

Look at magnetic fields

A
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11
Q

What are two ways to temporaliy create magnets?

A
  1. Single-touch method
  2. Electrical method
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12
Q

Describe the electrical method for making a magnet

A

This can be done by wrapping insulated copper wire arournd a steel or iron nail. When the ends of the wire are connected to a battery, the nail is magnetised.

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13
Q

Describe the single-touch method for making a magnet.

A

In this method, you stroke a steel bar from end to end several times in the same direction with one pole of the magnet.
Between strokes, the pole is lifted high above the bar, otherwise, the magnetism already induced may be weakend.

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14
Q

How can you demagnetise a temporary magnet more quickly than just leaving it?

A

By dropping or banging it on a hard surface

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15
Q

What happens a temporary magnet over time?

A

The magnetism decreases over time.

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16
Q

Where is a magnetic field the strongest?

A

At the poles.

17
Q

State the Law of Attraction and Repulsion of magnets.

A
  • unlike poles attract
  • like poles repel
18
Q

What are some of the dangers with magnets

A

They can interfere with sensitive medical equipment e.g. pacemaker

19
Q

What is an electromagnet?

A

This is a magnet made of a solenide with an iron core.

20
Q

How do you make an electromagnet?

A

When an electric current passes through a coil of wire (called a solenoid) it creates a magnetic field around it. The solenoid behaves like a magnet.

21
Q

What happens if you put an iron rod inside a solenoid?

A

The iron rod becomes magnetised making the magnetic field stronger.

22
Q

What is the iron rod inside a solenoid called?

A

Iron core

23
Q

What is the shape of a magnetic field around a solenoid?

A

It is the same as the magnetic field of a bar magnet.

24
Q

Name two advantages of electomagnets.

A
  1. The magnetic field of an electormagnet is much stronger than a bar magnet of a similar size.
  2. An electromagnet can be switched off as the magnetic field disappears when the electric is switched off.
25
Q

Name three things an electromagnet can be used for?

A
  1. Scrape metal crane
  2. Alarm bell
  3. Door bell
26
Q

How is an electromagnet used in an alarm bell?

A

Switch is closed
This completes the circuit and current flows
This causes the electro magnet to attract the arm/hammer to the bell causing a sound.
The movement of the arm/hammer breaks the circuit
Another spring pulls the arm/hammer back completing the circuit again and the process continues

27
Q

How is an electromagnet used in a door bell

A

Switch is closed
This completes the circuit and current flows
This causes the electro magnet to attract the arm/hammer to the bell causing a sound.
Releasing the switch breaks the circuit, switching off the electromagnet.
This causes the arm/hammer to swing across and hit the 2nd chime.

28
Q

How do you change the strength of an electromagnet?

A
  1. Change the voltage. Higher voltage stronger magnet.
  2. Change the number of coils. More coils stronger magnet.
  3. Add/remove an iron core. Adding an iron core makes the magnet stronger.

Physics year nine (3 decks)

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