Magnetic Fields Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What are the 3 rules when drawing magnetic patterns?

A
  • like poles repel
  • unlike poles attract
  • field lines from north to south
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How are magnetic fields produces in electric circuits?

A

moving charged particles within a wire

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When are magnetic field lines concentric?

A

long straight current carrying conductors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What do magnetic field lines of a solenoid resemble?

A

magnetic field lines of a bar magnet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the magnetic field lines of a solenoid?

A

uniform field with a solenoid core

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is magnetic flux density?

A

strength of the magnetic field

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is Newton’s third law applied to current carrying conductors?

A

wire and magnet experience equal and opposite forces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Within Flemming’s left hand rule which fingers represent which component?

A
  • thumb: motion (up/down)
  • index: field (N to S)
  • middle: current (direction)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the SI unit of magnetic flux density?

A

tesla (T)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

When does does magnetic flux density equal 1?

A

when a wire carrying a current of 1A placed perpendicular to the magnetic field experiences a force of 1N per metre of its length

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why do charged particles in magnetic fields move in a circular path?

A

because magnetic force is perpendicular to velocity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why is no work done when the particle moves in a circular path?

A

force has no component in direction travel so velocity remains constant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the centripetal force when a particle moves in a circular path?

A

BQV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is a velocity selector?

A

device used in instruments such as mass spectrometer to select charged particles of a specific speed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Define magnetic flux:

A

product of the component of magnetic flux density perpendicular to the area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Define magnetic flux linkage:

A

product of the number of turns in coil N and magnetic flux

17
Q

What units do magnetic flux and magnetic flux linkage use?

A

Weber (W)

18
Q

What is Faraday’s law?

A

the magnitude of the induced emf is directly proportional to the rate of change of magnetic flux linkage

19
Q

What is Lenz’s law?

A

the direction of the induces emf or current is always such to oppose the charge producing it

20
Q

How does an AC generator work?

A

a coil is rotated at a steady speed in a magnetic field

21
Q

How does magnetic flux linking the coil in an AC generator vary?

A

sinusoidally

22
Q

What is the negative gradient of a flux linkage against time graph equal to?

A

EMF

23
Q

What is supplied to the primary input coil of a transfprmer?

A

alternating current

24
Q

What does passing alternating current through a transformer cause?

A

varying magnetic flux in the soft iron core

25
Q

What does the iron core of a transformer ensure?

A

no magnetic flux is lost between the primary and secondary coil

26
Q

In accordance to Faraday’s law what is produced across the ends of a secondary coil in a transformer?

A

varying emf

27
Q

What are transformers used for?

A

to step up and step down voltages

28
Q

What is equal in a 100% efficient transformer?

A

output power and input power