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Practice # 6 AC Theory

Total questions: 20

Worksheet time: 10mins

Name
Class
Date
1.

When a conductor is moved through a magnetic field, an ________ is induced in the conductor.

a)

electromotive force (EMF)

b)

electro-galvanic current (EMC)

c)

electro-magnetic pulse (EMP)

d)

electrochemical reaction (ECR)

e)

electrostatic discharge (ESD)

2.

Whenever a voltage or current passes through a series of changes, returns to the starting point, and then again starts the same series of changes, the series is called a __________.

a)

cycle

b)

period

c)

alternation

3.

The frequency is the number of __________________ of AC per second (1 second).

a)

cycles

b)

waves

c)

periods

d)

alternations

e)

pulses

4.

The time required for a sine wave to complete one full cycle is called a ________________.

a)

alternation

b)

cyclic time

c)

period

5.

The distance that a waveform travels during a period is commonly referred to as a __________.

a)

wavelength

b)

period length

c)

sine length

6.

An ________________ of voltage or current is the induced voltage or current flowing at any instant during a cycle.

a)

intrinsic value

b)

average value

c)

induced value

d)

instantaneous value

e)

peak value

7.

The ____________ is the largest instantaneous value.

a)

power value

b)

average value

c)

induced value

d)

peak value

e)

minimum value

8.

The largest single positive value occurs when the sine wave of voltage is at 90°, and the largest single negative value occurs when it is at 270°. Peak value is 1.41 times the effective value. Regarding the above statements:

a)

Only #1 is true

b)

Only #2 is true

c)

Both #1 and #2 are true

9.

Effective value is also known as the __________ value or root mean square, which refers to the mathematical process by which the value is derived.

a)

MRS

b)

SMS

c)

RMS

d)

AMS

e)

TMS

10.

The effective value of a sine wave is actually a measure of the __________ of the sine wave.

a)

heating effect

b)

resistive effect

c)

frequency

d)

counter EMF

e)

amplitude

11.

When two waves, such as current and voltage are exactly in step with each other, they are said to be in _______________.

a)

conjunction

b)

parallel

c)

phase

d)

opposition

e)

discord

12.

When two waveforms go through their maximum and minimum points at different times, the two waveforms are said to be _______________ with each other.

a)

incongruent

b)

out of phase

c)

oblique

d)

synchronized

e)

aligned

13.

The waveform that reaches its maximum or minimum value first is said to _________ the other waveform.

a)

lag

b)

dominate

c)

lead

d)

precede

e)

follow

14.

Most aircraft using a 24-volt DC system have special equipment that requires a certain amount of __________________ AC current.

a)

400 hz

b)

115 hz

c)

50 hz

d)

60 hz

e)

220 hz

15.

DC flows constantly in only one direction with a constant polarity, whereas AC current flow changes __________________ at regular intervals.

a)

polarity and resistance

b)

direction and polarity

c)

voltage and current

d)

direction and intensity

e)

wattage and polarity

16.

Because more and more units are being operated electrically in airplanes, the power requirements are such that a number of advantages can be realized by using AC.

a)

1, 2, and 3 are correct statements.

b)

1 and 2 are correct statements.

c)

1 and 3 are correct statements.

17.

When a conductor is moved through a magnetic field, an emf is induced in the conductor. The __________________ can be used to determine the direction of the induced emf.

a)

generator left-hand rule

b)

voltmeter

c)

ammeter

d)

ohmmeter

18.

When a loop conductor is rotated in a magnetic field, a __________ is induced in each side of the loop.

a)

voltage

b)

current

c)

electrostatic field

d)

resistance

e)

magnetic field

19.

Generators used to produce an alternating current are called ____________________.

a)

DC generators or alternators.

b)

AC generators or commutators.

c)

AC generators or inducers.

d)

DC generators or inducers.

e)

AC generators or alternators.

20.

The value of an induced emf depends on three factors: 1. Material the wire is made from. 2. Temperature of the wire 3. Number of wires moving through the magnetic field 4. Strength of the magnetic field 5. Length of the wire 6. Speed of rotation Which of the following combinations are correct?

a)

1, 2 and 6

b)

3, 4 and 6

c)

3, 5 and 6