Magnetic Field & Forces

Question 1

Define what is meant by a Magnetic Field.

Answer 1

Is a region where a small, positively charged particle feels a force

Question 2

How are magnetic fields represented?

Answer 2

With field lines

Question 3

In which direction do field lines travel?

Answer 3

From NORTH to SOUTH

Question 4

What does the distance between the field lines represent?

Answer 4

The closer together the lines, the stronger the field.

Question 5

Draw a diagram of a Bar Magnet.

Answer 5

Question 6

Draw a Diagram of close together North and South poles.

Answer 6

Question 7

Draw a Diagram of LIKE poles being pushed towards each other.

Answer 7

The arrow is pouring at a neutral point we’re magnet fields cancel out

Question 8

What must be true for a Magnetic Field to be around a wire?

Answer 8

Wire must be carrying and electric current, therefore a magnetic field will be created.

Question 9

What are the field lines like around a Current carrying wire?

Answer 9

Question 10

What hand do you use to find the Magnetic Field around a Current carrying wire?

Answer 10

Right hand

Question 11

Show what a Magnetic Field around a Solenoid.

Answer 11

Question 12

What will a wire carrying a Current in a magnetic field experience?

Answer 12

A force

Question 13

Show a diagram of a Current carrying wire within a Magnetic Field.

Answer 13

Question 14

Which rule to you use to find the Resultant Force of a Current carrying wire within a Magnetic Field?

Answer 14

Flemings Left Hand Rule

Question 15

In which direction does the force act on a wire carrying a Current within a Magnetic Field?

Answer 15

Perpendicular to the Magnetic Field

Question 16

What happens to the Force if the Current carrying wire is parallel to the Magnetic Field?

Answer 16

There is no force

Question 17

State the components of Flemings Left-Hand Rule.

Answer 17

THUMB - Force (Motion)

First Finger - Magnetic Field

SeCond Finger - Conventional Current (positive to negative)

Remember - FBI

Question 18

Which way does Conventional Current go?

Answer 18

Positive to Negative

Question 19

The force on a wire is proportional to…

Answer 19

The Flux Density

Question 20

Define Magnetic Flux Density.

Answer 20

The force on one metre of wire carrying a Current of one amp at right angles to the Magnetic Field

Question 21

What is the Equation symbol for Magnetic Flux Density?

Answer 21

B

Question 22

What is Force Proportional to when a Current is at 90 degrees to the Magnetic Field?

Answer 22

Force is proportional to the…

• Current, I
• Length of wire in the field, l
• Flux Density, B

Question 23

What is the equation for the force of a Current carrying wire when it is 90 degrees to the magnetic field?

Answer 23

F = BIL

F - Force (N)

B - Flux Density (T, Tesla’s)

L - Length of wire in the field (m)

Question 24

Is Flux Density a Scalar or a Vector?

Answer 24

Vector

Question 25

What is Flux Density measured in?

Answer 25

Teslas, T

Question 26

When is the Force of a Current carrying wire within a Magnetic Field at its greatest?

Answer 26

When it is perpendicular to the field

Question 27

What is the equation for the Force of a wire acting an angle to the magnetic field?

Answer 27

F = BIL sin θ

Question 28

Forces act on (……………..) in Magnetic Fields

Answer 28

Charged Particles

Question 29

Define Electric Current.

Answer 29

Flow of charge, Q per unit time.

Question 30

What is the equation for the velocity of a charged particle?

Answer 30

V = L / t

V - Velocity

L - Distance travelled

t - Time

Question 31

Derive the equation F = Bqv.

Answer 31

Use F = BIL

And I = Q / t

And L = vt

Substitute into F = BIL

F = B q/t vt - the t’s cancel out.

F = Bqv or F = Bqv sin θ

Question 32

What is the equation for the Force acting on a charged particle in a magnetic field?

Answer 32

F = Bqv sin θ

F - Force (N)

B - Magnetic Flux Density (T)

q - charge on the particle (C)

v - Velocity of the particle (ms*-1)

θ - angle between the current and field lines