ch20

Question 1

A magnetic field

Answer 1

s a region of space where a force acts on a moving charge or a magnet pole

Question 2

motor effect

Answer 2

Phenomenon when a current-carrying conductor placed in a magnetic field experiences a force, due to the interaction of the magnetic field with that produced by the current-carrying conductor

Question 3

force exerted on the conductor

Answer 3

F = BILsinθ where B is magnetic flux density (constant)(l in length and i is current)

Question 4

Magnetic flux density

Answer 4

numerically equal to the force per unit current per unit
length on a straight wire placed at right angles to a uniform magnetic field. it is measured in tesla T

Question 5

The force on a particle of charge q moving at speed v at an angle θ to a uniform
magnetic field of flux density B is given

Answer 5

F = Bqv sinθ. (memorize proof)

Question 6

Hall voltage VH

Answer 6

BI/(ntq) see proof

Question 7

Helmholtz coils

Answer 7

Two identical flat coils, with the same current in each, positioned so that their planes are parallel and separated by a distance equal to the radius of either coil

Question 8

Magnetic flux

Answer 8

x is the product of the magnetic flux density and the area normal to the lines of flux.
Φ = BAsinθ The unit of magnetic flux is the weber (Wb).

Question 9

magnetic flux linkage

Answer 9

= NΦ = BAN This magnetic flux passes through the N turns of the coil

Question 10

n Faraday’s law of electromagnetic induction

Answer 10

The e.m.f. induced is proportional to the rate of change of magnetic flux linkage

Question 11

Lenz’s law

Answer 11

The direction of the induced e.m.f. is such as to cause effects to oppose the change
producing it.

Question 12

induced e.m.f. E is given by

Answer 12

E = −Δ(NΦ)/Δt