Magnetic Fields

Question 1

Define magnetic flux density
-state other terms for it
-state symbol

Answer 1

force acting per unit length of conductor, per unit current on a conductor placed perpendicular to the field
-magnetic field intensity
magnetic field strength
-B

Question 2

Define magnetic flux
-state symbol

Answer 2

Product of the area of a surface and the magnetic flux density perpendicular to the surface
- ø
- Ø= AB

Question 3

force on a conductor equation

Answer 3

F=BIL Sin pheta

Question 4

Force on charge equation

Answer 4

F= BQv sin pheta

Question 5

State SI Unit of flux
-define it

Answer 5

Weber(Wb)
1 Tesla metre-squared

Question 6

Equation of flux
And Equation of flux linkage

Answer 6

Ø = AB sin pheta
NØ = N AB sin pheta

Question 7

State the SI unit of magnetic flux density
-Define it

Answer 7

Tesla
-The magnetic field intensity of a uniform B that exerts a force per unit length of 1 Nm-1 on a conductor carrying a current of 1 A placed perpendicular to the field

(Using F/L=BI sin pheta)
B=> F/L=> I => 90°

Question 8

State equations of B in (in terms of material)
-wire
-coil
-solenoid

Answer 8

• u I / 2 pi r (current per circumference * material property)
• u N I / 2 r (dependent on size of coil instead of distance from it and number of turns)
• u n I (depending on number of turns per length of solenoid)

N : num of turns
n : num of turns per length

Question 9

Conditions for moment (1 force vs 2 force)

Answer 9

1 force
-Current gives rise to force
-force vertical
-force does not act through pivot

2 force
Forces do not act through the same line
-forces not equal and opposite (net force)