Chapter 23 Magnetic Fields Flashcards

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

How are magnetic field lines drawn?

A
  • Arrow of the magnetic fields shows the direction in which the force acts
  • Equally spaced lines indicate a uniform field
  • The field is stronger when the lines are closer together
  • Like polls repel
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When a wire carries current…

A

…A magnetic field is produced

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

What happens when a charged particle moves?

A

It creates a magnetic field

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

What is the right hand grip rule? What does it show?

A

It shows where the direction of the magnetic field based off a current flowing through a wire.
Make your right hand into a thumbs up shape.
The direction of your thumb is the direction of the current through a wire.
The direction of the rest of your fingers shows where the magnetic field lines are.

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

What is the strength of a magnetic field measured in?

A

Tesla

units T

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

What is flemings left hand rule and what does it show?

A

It shows the force applied to a wire with current flowing through it when it is placed in a magnetic field.
- ThuMb indicates motion, the direction of the force
- First finger is for Field, the direction of the field
- SeCond finger is for the direction of the current flowing through a wire
If you have 2 of the 3 parts you can find the other one

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

What is thumb on flemings left hand rule?

A

Motion, direction of the force

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

What is the second finger for flemings left hand rule?

A

Direction of the current

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the first finger for flemings left hand rule?

A

Magnetic field direction

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

What is the equation to find the magnitude of the force on a wire placed in a magnetic field?

A
F = BILSinθ
F = Force
B = Magnetic flux density (tesla)
L = Length of wire in field
Sinθ = Angle between magnetic field and current direction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the equation for the force on a wire when it is 90* to the magnetic field?

A

B = F / IL

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

How is the magnetic flux density calculated in a lab?

A

A horse shoe magnet is placed side ways on a balance. A wire with a know current is placed between the magnet. The amount of wire in the magnet is then measured. Then the force on the balance is read and the equation: B = F/IL is used

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

What happens to electrons passing through a magnetic field?

A

they follow the magnetic field lines

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

What is the equation for charged particles through a magnetic field?

A
F = BeV
F = Force
B = The magnetic flux density 
e = Charge on an electron or protons (or the charge for a particle)
v = Velocity of the particle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the path for an electron passing through a uniform magnetic field? Why?

A

It is circular path because the force is always perpendicular to the direction of travel

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

What is the equation for a particle passing through a uniform field?

A
r = mv / BQ
r = radius
m = mass
v = velocity
B = Magnetic Flux density
Q = Charge
17
Q

How is the equation for a particle passing through a uniform field derrived?

A
F = mv^2 / r (Centripetal force equation)
F = BQv 
BQv = mv^2 / r 
BQ = mv / r
r = mv / BQ
18
Q

What does the equation r = mv / BQ show us?

A

It shows us that the radius is proportional to speed and mass. r ∝ v
So a larger particle moves in larger circles. r ∝ m
Stronger magnetic fields make particles move in smaller circles. r ∝ 1/B
Particles with greater charges move in smaller circles.
r ∝ 1 / Q

19
Q

What is a velocity selector?

A

It is a device that uses electric and magnetic fields to select charged particles of a specific velocity.

20
Q

What does a velocity selector consist of?

A

It consists of a magnetic field perpendicular to an electric field.

21
Q

How does a velocity selector work?

A

Charges are deflected by the magnetic and electric fields and only charges of a specific speed will these deflections cancel out and travel in a straight line emerging from the velocity selector.