Chapter 7: Magnetisim

Question 1

The two necessary conditions for the generation of magnetic fields are:

Answer 1

charge and movement of that charge

Question 2

The SI unit of the magnetic field is the:

Answer 2

Tesla (1 T = 1 Ns/mC)

Question 3

Small magnetic fields are sometimes measured in:

Answer 3

gauss

Question 4

1 Tesla is equivalent to how many gauss?

Answer 4

10⁴ (1 gauss = 1 X 10^-4 T)

Question 5

Diamagnetic materials are:

Answer 5

weakly antimagnetic materials in which all electrons are paired; “non-magnetic”

Question 6

Paramagnetic materials are:

Answer 6

materials that possess some unpaired electrons and become weakly magnetic in an external magnetic field

Question 7

Ferromagnetic materials are:

Answer 7

strongly magnetic materials that possess some unpaired electrons with atoms organized in magnetic domains

Question 8

Curie temperature is:

Answer 8

the temperature for all ferromagnetic materials above which they are paramagnetic and below which they are strongly and permanently magnetic

Question 9

Magnetic field lines are:

Answer 9

circular

Question 10

Current carrying wire generates a:

Answer 10

magnetic field in its vicinity. The net magnetic field of the current is equal to the vector sum of the magnetic fields of all the individual moving charges that comprise the current.

Question 11

Electric current is:

Answer 11

the flow of charge between two points of different electric potentials connected with a conductor

Question 12

Equation to determine the total electric current passing through a conductor per unit of time:

Answer 12

i = Δq / Δt

where i = the magnitude of the current, Δq = the amount of charge passing through the conductor, and Δt = the time

Question 13

The SI unit of current is:

Answer 13

ampere (1 A = 1 C/s)

Question 14

The direction of current, by convention, is the direction in which:

Answer 14

positive charge would flow from higher potential to lower potential. The direction of current is opposite to the direction of electron flow.

Question 15

Equation to determine the magnitude of the magnetic field produced by a straight current-carrying wire at a chosen point in space:

Answer 15

B = u₀i / 2πr

where B is the magnetic field at distance r from the wire, u₀ is the permeability of free space (4π X 10^-7 T)

Question 16

The shape of the magnetic fields surrounding a current is:

Answer 16

concentric perpendicular circles of magnetic field vectors

Question 17

To determine the direction of the field vectors in a magnetic field, use the:

Answer 17

First right hand rule.

1) right-hand thumb points in direction of current
2) your right fingers curl in and mimic the circular magnetic field lines that curl around the current

Question 18

Equation to determine the magnitude of the magnetic field produced by a circular loop of current-carrying wire at the center of the loop:

Answer 18

B = u₀i / 2r

where B is the magnetic field at distance r from the wire, u₀ is the permeability of free space (4π X 10^-7 T)

Question 19

Straight current carrying wires create magnetic fields that are:

Answer 19

perpendicular concentric circles surrounding the wire

Question 20

Circular loops of current carrying wire create magnetic fields that are:

Answer 20

perpendicular concentric circles surrounding the wire

Question 21

Equation to determine the magnetic force on a moving charge in an external magnetic field:

Answer 21

F = qvBsinØ

where q is the charge, v is the velocity of the charge, B is the magnitude of the magnetic field, and Ø is the smallest angle between vector qv and the magnetic field vector B

Question 22

If a charge is moving with a velocity that is parallel or antiparallel to the magnetic field vector, it will experience:

Answer 22

no magnetic force

Question 23

To determine the direction of magnetic force on a moving charge, use the:

Answer 23

Second right hand rule:

1) right-hand thumb points in the direction of vector qv (positive charge in the direction of v, negative charge opposite direction of v)
2) Fingers point towards the direction of the magnetic field
3) Your palm then indicates the direction of the magnetic force vector F on the moving point charge q.

Question 24

Magnetic field vectors going into the page are represented by:

Answer 24

X’s

Question 25

Magnetic field vectors coming out of the page are represented by:

Answer 25

Dots

Question 26

The direction of the magnetic force on a negative charge moving through a magnetic field is ___ to the direction of the magnetic force acting on a positive charge moving in the same direction.

Answer 26

opposite

Question 27

Charges moving into a magnetic field perpendicular to the magnetic field vector will assume what kind of motion?

Answer 27

uniform circular motion with constant velocity; the centripetal force in the magnetic force

Question 28

When a charge is moving in uniform circular motion due to an external magnetic field, a change in strength of the magnetic field will result in:

Answer 28

a change in the radius of the circular pathway, not a change in the magnitude of its velocity

Question 29

Formula for centripetal force of a charged particle moving perpendicular to the magnetic field vector:

Answer 29

F = qvb = mv²/r

Question 30

Equation used to determine the magnetic force on a current carrying straight wire in a uniform external magnetic field:

Answer 30

F = iLBsinØ

where i is the current, L is the length of the wire, and Ø is the angle between the current and the magnetic field (B)

Question 31

To determine the direction of magnetic force on a current carrying wire, use the:

Answer 31

Third right hand rule:

1) right-hand thumb points in the direction of the current
2) Fingers point towards the direction of the magnetic field
3) Direction of your palm then indicates the direction of the magnetic field vector

Question 32

A current carrying wire placed in an external magnetic field will experience a magnetic force as long as:

Answer 32

the current has a directional component that is not parallel or antiparallel to the magnetic field vector.