Magnetism

Question 1

Uniform magnetic field (B)

Answer 1

Have const magnitude + point in one direction in region in question

Question 2

B vector

Answer 2

Out of page - dot

Into page - X

Question 3

B lines

Answer 3

Describe strength + direction of B
Points from north to south
denser lines, greater strength of B at this point

Question 4

Units of B

Answer 4

Tesla 1 T= 1 Ns/ mC

Gauss: 1 Gauss= 10^-4 Tesla used when in tesla very big #

Question 5

Permeability of free space

Answer 5

Mju0

= 4 pi* 10^-7 N/ A^2

Question 6

How B can be created?

Answer 6

In 2 ways:

1. By moving qs
2. By permanent magnet

Question 7

B created by long, I carrying wire

Answer 7

Wire - symmetrical object. I flows in one direction with const magnitude.
B also symmetrical.
RHR: thumb along direction of I, fingers - direction of B- circular, concentric about wire
farther from wire, less intense B strength
B=(mj0*I/2pir) as r gets larger B drops. B dp to I
R -perpendicular distance fr wire
Gives magnitude of B at any perpendicular distance from wire

Question 8

B created by circular wire loop

Answer 8

RHR for loop:
Thumb along direction of I in loop, curl fingers into loop- direction of B
At loop center B - const + flows straight through loop
B center of loop= m0I/2r, bigger loop, smaller B in center

Question 9

Requirements for object to feel F due to B

Answer 9

1. Must have non0 q
2. Must be in motion
3. Must not be moving parallel /anti parallel to direction of B

Question 10

B has no effect on:

Answer 10

• neutral particles

- particles that move along / against direction of B

Question 11

Magnetic F on q

Answer 11

F=qvB*sin terra
Terra - angle btwn v vector + B direction
When vector for v parallel to direction of B terra = 0, no magnetic F
In this formula do not need - sign for q

Question 12

RHR for direction of magnetic F

Answer 12

Thumb in direction of v of particle, fingers in direction of B.
If + q, palm points in direction of F.
If- q, palm points away fr direction of magnetic F

Question 13

Magnetic F on q

Answer 13

Always perpendicular to direction of travel + direction of B
q in B always accelerate perpendicular to direction of travel
W done by B - always 0
v of q stays const under B

Question 14

q moving in uniform B

Answer 14

Moves in circle
F on q is towards center in centripetal motion
Newtons 2nd law for r of circle
Fmagnetic= ma
qvB=mv^2/r
R=mv/qB circle - larger for faster qs, smaller for strong Bs

Question 15

Magnetic F on I carrying wire

Answer 15

F= ILB*sinterra

Terra -angle btwn B direction + direction of I

Question 16

Magnetic materials

Answer 16

Diamagnetic
Paramagnetic
Ferromagnetic

Question 17

Diamagnetics

Answer 17

Made of atoms with no unpaired es
Have no net B
Repel by either pole of magnet
Wood, plastic, water, glass, skin

Question 18

Paramagnetics

Answer 18

Have unpaired es
Have net magnetic moment dipole
Will become weakly magnetized in presence of external B.
Al, copper, gold

Question 19

Ferromagnetics

Answer 19

Have unpaired es + permanent atomic magnetic dipole
Become strongly magnetized under external B / under certain temp
Have critical temp- curie temp: above it become paramagnetic, below it- magnetized
Me bar magnets, Ni, Co

Question 20

Electric I

Answer 20

Flow of qs

Question 21

Magnitude of I

Answer 21

amount of q passing through conductor /unit of t
I=q/t
SI units -ampere 1 A= 1C/s

Question 22

Actual I flow

Answer 22

Fr lower potential to higher potential

Es flow

Question 23

Conventional I

Answer 23

Flow of + charges

Fr higher potential to lower potential