Magnetic Fields

Question 1

Explain Flemings left hand rule

Answer 1

Thumb - motion of wire
First finger - magnetic field
Second figure - electric current

Question 2

State the equation for the force on a conductor

Answer 2

F=BIL
B is magnetic field in teslas
I is current
L is length of wire

Question 3

Define magnetic flux density

Answer 3

The magnetic force experienced by a current varying conductor placed at right angles to a magnetic field

Question 4

Define the tesla

Answer 4

The magnetic flux density is 1T when a wire carrying a current of 1A placed at right angles to the magnetic field experiences a force of 1N per metre of its length

Question 5

State the equation for the force acting on a particle traveling at right angles to a magnetic field

Answer 5

F= BQv
Where B is magnetic field density in T
Q is charge of he particle in C
v is the velocity of the particle in M/s

Question 6

describe the circular orbits of charged particles moving in a plane perpendicular to a uniform magnetic field.

Answer 6

In a uniform magnetic field charged particles will always be moving perpendicular to the field. As the field bends, so does the orbit of the particle as it is held in place by centripetal force

Question 7

Describe how magnetic fields are represented

Answer 7

• magnetic field lines come out of North Poles and go into south poles
• the direction of a field line at any point in the field shows the direction of the force that a ‘free’ magnetic North Pole would experience at that point
• the field is strongest where the field lines are closest together