Electromagnetism Flashcards

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1
Q

What is a magnetic field?

A

A region where magnetic materials experience a force

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2
Q

Which direction do magnetic field lines point?

A

From north to south

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3
Q

3 magnetic metals?

A

Iron,nickel and copper

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4
Q

What does magnetically soft mean?

A

Easy to magnetise and de magnetise (eg iron)

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5
Q

What does magnetically hard mean?

A

Difficult to magnetise and demagnetise (eg steel)

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6
Q

Explain experiment 1 (iron fillings)

A

-Place a magnet under paper
-put iron fillings on the top and tap paper
-should show magnetic field lines

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7
Q

What are the advantages and disadvantages of experiment 1?(iron fillings)

A

-precise and allows clear image
-can’t see direction

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8
Q

Explain experiment 2(plotting compass)

A

-place magnet on paper
-mark North Pole
-move compass around magnet
-mark North Pole again

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9
Q

Advantages and disadvantages of experiment 2?(plotting compass)

A

-shows clear direction
-low resolution field lines

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10
Q

What is the right hand grip rule used to find?

A

Direction of Current and magnetic field

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11
Q

In the right hand grip rule what do the thumb and fingers represent?

A

Thumb- current
Fingers- magnetic field

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12
Q

What is a solenoid?

A

A solenoid is a cylinder coil of wire acting as a magnet when carrying electric current.

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13
Q

Explain the motor effect

A

When a current-carrying wire is put between magnetic poles, the two magnetic fields affect on another. This result is a force on the wire. This can cause the wire to move.

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14
Q

What does flemmings left hand rule tell you?

A

Movement
Magnetic field (N to S
Current (+ to -)

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15
Q

In Flemings left hand rule, what does the thumb represent

A

Movement

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16
Q

In Flemings left hand rule, what does the first finger represent

A

Field (magnetic field)
North to south

17
Q

In Flemings left hand rule, what does the second finger represent

A

Current
(+ to -)

18
Q

In a simple direct current electric motor what 4 factors can speed it up

A

-higher current
-more coils
-a soft iron core
-stronger magnetic coil

19
Q

How do loudspeakers work?

A

-a.c electrical signals from an amplifier are fed to a coil of wire in the speaker which is wrapped around the base of a cone
-the coil is surrounded by a permanent magnet so the a.c signals cause a force on the coil and make it move back and forth
-these movements cause the cone to vibrate and creates sounds

20
Q

What is electromagnetic induction?

A

The creation of a voltage (and maybe current) in a wire which is experiencing a change in magnetic field

21
Q

What are 2 ways of generating electricity

A

-move a coil of wire in a permanent magnetic field
-move/rotate a permanent magnet within a coil of wire

22
Q

How to increase voltage/current?

A

-increase number of coils
-use a stronger magnet
-move magnet faster