Deck 18: Electromagnetic Induction

Question 1

____ law is useful in determining induced current direction in more complex machinery.

A)Fleming's
B)Edison's
C)Lenz's
D)Myer's

Answer 1

C

Question 2

An induced voltage or induced current is one that is produced by the action of magnetic forces rather than by chemical action or other methods.

Answer 2

True

Question 3

All generators operate on the principle of cutting flux lines with the relative motion of magnetic fields and coils of wire.

Answer 3

True

Question 4

The amount of emf induced is proportional to the product of ____ factors that determine the rate of cutting magnetic flux.

A)two
B)three
C)four
D)five

Question 5

To generate a useful voltage, we can move a coil through a magnetic field.

Question 6

The induction process in rotating machines produces AC, and if direct current (DC) is needed, it can be obtained from AC by using rectifiers.

Question 7

Not all generators are designed to maintain coils within a magnetic field but, instead, hold a magnet within a rotating coil.

Question 8

Commercial generators in the United States are standardized to produce ____ cycles per second.

A)30
B)60
C)90
D)120

Question 9

____ law states that an induced voltage or current opposes the motion that causes it.

A)Edison's
B)Brush's
C)Fleming's
D)Lenz's

Question 10

The relative ____ wire and magnetic field always induces a voltage, or emf.

A)friction between
B)motion of
C)magnetism of
D)currents between

Question 11

The ____ generators built contain stationary coils in which useful current is induced by a rotating magnet.

A)largest
B)smallest
C)newest
D)oldest

Question 12

When mechanical energy must be expended to rotate a coil within a magnetic field and cut the lines of flux, this energy is provided by engines called flux movers.

Question 13

The relation of direction of motion of the wire in a field to direction of induced emf can be determined by Fleming's right-hand rule.

Question 14

An emf is produced in a stationary coil when a bar magnet is withdrawn from, or inserted into, the coil so that the lines of force, moving with the magnet, ____ the wires of the coil.

A)move away from
B)cut across
C)move into
D)rest on top of

Question 15

The production of an induced voltage requires a conductor (generally in the form of a coil), a magnetic field, and ____ motion between the two.

A)transient
B)nonpolarized
C)static
D)relative

Question 16

A greater voltage output can be obtained by using a weaker magnet and/or coils with more turns.

Question 17

An alternate way of stating Lenz's law is that an induced voltage or current opposes a change of magnetic field.

Question 18

When lines of force are cut by wire coil, the relationship of voltage measurements to magnetic field measurements is this: To produce 1 volt, the wire must cut ____ lines of flux per second.

A)100,000
B)1,000,000
C)10,000,000
D)100,000,000

Question 19

Cutting 1,000,000 webers/second results in the generation of 1 volt.

Question 20

The term emf is known as alternating voltage and can be made visible on an instrument known as an ____.

A)oscilloscope
B)oscillometer
C)alternating scope
D)alternate voltmeter