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Physics > Physics Topic 7 > Flashcards

Physics Topic 7 Flashcards

1
Q

A magnet is any material or object that produces a ________ field.

A

magnetic

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2
Q

Give 3 examples of magnets:

A

The Earth
A horseshoe magnet
A bar magnet

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3
Q

The arrows on the magnetic field lines always point:

A

Out from the north and into the south

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4
Q

The strength of a magnetic field is shown by the _______ of the magnetic field lines.

A

density

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5
Q

Magnetic field lines can show (Give 2):

A

-> Whether two magnets would attract or repel
-> The strength of the magnet at a particular point
-> The direction that a small compass would point at that point

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6
Q

How can you tell which parts of the magnet diagram has the strongest magnetic field strength?

A

Field lines which are closer together

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7
Q

A magnetic m_______ is any material or object that can be influenced by a magnetic field, and has the potential to become a magnet.

A

material

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8
Q

Which of the following elements are magnetic?
Iron
Nickel
Copper
Cobalt

A

Iron
Nickel
Copper
Cobalt

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9
Q

Which type of magnetism is it when a magnetic material temporarily becomes a magnet when it’s placed close to a permanent magnet?

A

Induced magnetism

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10
Q

Permanent magnets always produce their ___ magnetic field
Temporary / induced magnets only produce a magnetic field in the ________ of another magnet

A

Permanent magnets always produce their own magnetic field
Temporary / induced magnets only produce a magnetic field in the presence of another magnet

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11
Q

The force between a permanent and an induced magnet will:

A

Always be attractive

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12
Q

Magnetic materials that gain and lose magnetism quickly are called magnetically ____ materials.
Magnetic materials that gain and lose magnetism slowly are called magnetically ____ materials.

A

soft
hard

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13
Q

An example of a magnetically soft material is ____.
And example of a magnetically hard material is _____.

A

iron
steel

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14
Q

When an e_______ current flows through a material, a magnetic field is always p_______

A

electrical
produced

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15
Q

The right hand rule can tell us the…

A

… direction of the magnetic field induced by a flowing current.

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16
Q

In the _____ ____ rule, the thumb is placed following the same direction as the c______ is travelling, and the fingers are the curled in the direction of the magnetic field l____.

A

right hand
current
lines

17
Q

In an electromagnet, a current is required to produce the magnetic field.
When the current is switched off, the magnetic field:

A

disappears

18
Q

Describe the 3 ways to increase the strength of an electromagnet.

A

Increase the current
Increase the number of turns in the solenoid, while keeping the length the same
Reduce the length of the solenoid while keeping the number of turns the same
Add a soft iron core

19
Q

What is the motor effect?

A

A current carrying wire in the presence of a magnetic field will experience a force.

20
Q

To experience the full force, a current carrying wire must be placed _____________ to the magnetic field.

A

perpendicular

21
Q

Fleming’s left hand rule can be used to tell us…

A

… the direction of the force experienced by a current carrying wire in a magnetic field.

22
Q

Fleming’s Left Hand Rule)
The thumb represents…

A

The direction of the force

23
Q

Fleming’s Left Hand Rule)
The index represents…

A

The direction of the magnetic field

24
Q

Fleming’s Left Hand Rule)
The middle represents…

A

The direction of the current

25
Q

The magnetic field strength (also known as magnetic flux density) is measured in:

A

Teslas (T)

26
Q

A wire carrying a current of 2 A is perpendicular to a magnetic field of 15 T. The length of the wire in the field is 0.2 m.
What is the force experienced by the wire?

A

2 x 15 x 0.2 = 6N

27
Q

A wire carrying a current of 6 A is perpendicular to a magnetic field of 30 T. The length of the wire in the field is 0.1 m.
What is the force experienced by the wire?

A

6 x 30 x 0.1 = 18N

27
Q

How does the split ring commutator ensure the coil rotates in one direction? 4 steps

A

1) The split-ring commutator swaps the positive and negative connections every half turn.
2) Therefore, the direction of the current through the coil reverses every half turn.
3) This means that the forces acting on the coil will always be acting in the same direction.
4) This causes the coil to rotate continuously in one direction.

28
Q

Overall, electric motors use e__________ to create a rotational m_____.

A

electricity
motion

29
Q

Give 2 ways to increase the speed of rotation in an electric motor:

A

Add more turns to the coil
Increase the magnetic field strength / magnetic flux density of the magnet
Increase the current in the coil

30
Q
A

Physics (10 decks)

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