Midterms (Chapter 14. Part 3)

Question 1

left-hand rule for solenoids
states that if the fingers of the left hand encircle the coil in the same direction as ____ flow, the thumb points in the direction of the _____ pole.

Answer 1

electron, north

Question 2

The physical motion resulting from
the forces of two magnetic fi elds is
called

Answer 2

Motor Action

Question 3

Motor action always tends to produce motion from a ______ field toward a _____ field.

Answer 3

stronger, weaker

Question 4

A conductor will have an induced
current or voltage only when
there is relative _____- between the wire
and ______ field.

Answer 4

motion, magnetic

Question 5

polarity of an induced voltage is
determined by

Answer 5

Lenz’s law

Question 6

For a conductor being moved through a magnetic field, the amount of induced voltage is determined by the rate at which the conductor cuts the _________ and by the number of _______ lines that are cut by the conductor.

Answer 6

magnetic flux

Question 7

Degaussing is done with

Answer 7

alternating current.

Question 8

Hysteresis losses increase with ______
frequencies.

Answer 8

higher

Question 9

The saturation of an iron core occurs when all of the molecular dipoles and magnetic domains are aligned by the ________ and the flux density cannot be increased in the core when the ______ is increased.

Answer 9

magnetizing force, field intensity

Question 10

The unit of field intensity is the

Answer 10

At/m and oersted.

Question 11

For a single conductor carrying an
alternating current, the associated
magnetic field is at _____ angles to the direction of current.

Answer 11

right

Question 12

The magnetic field surrounding a solenoid is like ____ magnet

Answer 12

Permanent magnet

Question 13

For a relay, the holding current is defined as the minimum amount of relay coil
current required to _____ a relay
energized.

Answer 13

keep