magnetic field

Question 1

how are magnetic fields produced

Answer 1

1. permanent magnet
2. moving charge

Question 2

direction of magnetic field

Answer 2

always from north to south

Question 3

properties of uniform magnetic field

Answer 3

1. strength is the same at all points
2. parallel equal spaced lines

Question 4

define magnetic flux density

Answer 4

the force acting per unit current per unit length on a wire placed at right-angles to the magnetic field

Question 5

equation force act on a current-carrying conductor placed in a magnetic field

Answer 5

F = B * I * L * sinθ
F=force N
B=magnetic flux density/ magnetic field strength; T (tesla)
I=current A
L=length m
θ=angle btw B and I
*F is always perpendicular to I

Question 6

when is force act on a current-carrying conductor placed in a magnetic field maximum and minimum

Answer 6

1. maximum when I perpendicular to B, F = IBL
2. minimum when I parallel to B, F= 0

Question 7

direction of current flow is always

Answer 7

positive to negative, in opposite direction to the motion of electron

Question 8

Fleming’s left hand rule

Answer 8

thumb = force
index = field
middle = current

Question 9

another way of using other than fleming’s left hand rule

Answer 9

use right hand:
1. thumb = current
2. other finger = field
3. palm= force if charge is positive
4. back of hand = force if charge is negative

Question 10

what does x and dot represent in 3D drawing

Answer 10

1. cross => into the page
2. dot => out of the page

Question 11

equation of magnetic force on a moving charge

Answer 11

F = B * v * Q * sinθ
F=force N
B=magnetic flux density/ magnetic field strength; T (tesla)
v=speed of charge ms^-1
Q=charge C
θ=angle btw B and vwh

Question 12

motion of moving charge in uniform magnetic field

Answer 12

circular motion since Fmag is perpendicular to v
=> F mag = Fc

Question 13

when is magnetic force on moving charge the greatest and smallest

Answer 13

θ=0 smallest, 90 greatest

Question 14

what is hall voltage

Answer 14

The potential difference produced across an electrical conductor when an external magnetic field is applied perpendicular to the current through the conductor

Question 15

how is hall voltage produced

Answer 15

when a magnetic field applied
=>pushes positive charge to one side and negative on the other side
=> create voltage

Question 16

equation for Hall voltage

Answer 16

VH = (B * I) / (n * t * q)
B=magnetic flux density; T
I=current; A
q=charge of electron; C
n=density of electron; m^-3
t=thickness of conductor; m