Magnetism

Question 1

Magnetic Fields

Answer 1

Field vectors created by moving charges, currents in wires, and permanent magnets that exert forces on moving charges and permanent magnets.
Units: Tesla = N s/ m C
1 T = 10^4 gauss

Question 2

Magnetic Force

Answer 2

F = q v B sin θ

Question 3

What magnitude of force do charges moving parallel to a magnetic field feel?

Answer 3

No magnetic force because the angle is 0 degrees.

Question 4

Which direction is the magnetic force pointing when a charge is moving towards the top of the page and the magnetic field is pointing into the page?

Answer 4

The magnetic force is towards the left.

Question 5

Does the magnetic force do work?

Answer 5

No, because the magnetic force on a moving charged particle is always perpendicular to both the velocity of the charge and the magnetic field direction.

Question 6

What is the centripetal force of a charged particle moving perpendicular to a constant, uniform magnetic field?

Answer 6

Magnetic Force: F = qvB = m v^2/ r

Question 7

What is the orbit radius for a charge undergoing uniform circular motion due to a magnetic field?

Answer 7

r = mV/ qB

Question 8

What is the magnetic field for a charged particle moving perpendicular to a constant, uniform magnetic field?

Answer 8

B = mv/ qr

Question 9

Current

Answer 9

The flow of charge across ΔV, measured by the amount of charge passing through over a unit of time. Electrons from from lower potential to higher potential, but current moves in the direction of positive charge from high to low potential. Therefore, currents in magnetic fields behave similarly to moving positive charges.
I = Δq/ Δt
Units: Ampere = C/ s

Question 10

Force on a current-carrying wire

Answer 10

F = iLB sin θ

Question 11

Magnetic Field Lines

Answer 11

Out of the north poles and towards the south poles

Question 12

Diamagnetic Materials

Answer 12

Diamagnetic material atoms have no net magnetic field, but they will be repelled from the pole of a strong bar magnet.

Question 13

Paramgnetic Materials

Answer 13

Paramagnetic material atoms do have randomly oriented atomic fields that produce a net magnetic field; however, under certain conditions, the atomic fields can align and the material will be attracted towards a pole of a strong bar magnet.

Question 14

Ferromagnetic Materials

Answer 14

Ferromagnetic material atoms have magnetic fields when the temperature is below the Curie temperature.

Question 15

Magnetic Field produced by a current carrying wire

Answer 15

B = μ0 I/ 2πr
μ0 = 4π X 10^-7 T m/ A = 1.26 X 10^-6  T m/ A

Question 16

Magnetic Field produced by a loop-wire

Answer 16

B = μ0 I/ 2r only at the center of the loop