NAVEDTRA 14174A, NEETS Mod. 2, Ch.1 Flashcards Preview

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Flashcards in NAVEDTRA 14174A, NEETS Mod. 2, Ch.1 Deck (28):
1

Which type of current regularly changes direction?

Alternating

2

What is the amplitude of direct current in a wire when a coulomb of electrons moves past a point in a wire in one second and all of the electrons are moving in the same direction?

One ampere

3

Which type of current is practically used by all modern commercial electric power companies?

Alternating

4

Which type of device can step up or down alternating voltages amplitudes?

Transformer

5

Which type of patterns are plotted on graph paper that result from changes in amplitude with respect to time?

Waveform

6

What is the most commonly used means for producing or using electricity?

Magnetism

7

What year did Hans Christian Oersted discover a definite relationship between magnetism and electricity?

1819

8

Which conductor rule can the relation between the direction of the magnetic lines of force around a conductor and the direction of electron current flow in the conductor be determined?

Left-Hand rule

9

Which unit indicates one cycle per second?

Hertz (Hz)

10

What is the number of complete cycles of alternating current or voltage completed each second referred to as?

Frequency

11

What is frequency always measured and expressed in?

Hertz

12

What is the time required to complete one cycle of a waveform called?

Period

13

What is the distance from zero to the maximum value of each alternation called?

Amplitude

14

What is the distance along the waveform from one point to the same point on the next cycle called?

Wavelength

15

How many maximum or AC peak values during each complete cycle of AC are there?

Two

16

What are alternating voltage and current usually expressed in?

Effective values

17

Which alternating voltage or current value is the value of voltage or current at one particular instant?

Instantaneous

18

What is the value of alternating voltage or current that will have the same effect on a resistance as a comparable value of direct voltage or current will have on the same resistance?

Effective

19

Which method is the rate at which heat is produced in a resistance form a convenient basis for establishing an effective value of alternating current known as?

Heating effect

20

Which law states that current is directly proportional to the applied voltage?

Ohms law

21

What are two sine waves that are precisely in step with one another said to be?

In phase

22

What is the amount by which one sine wave leads or lags another sine wave measured in?

Degrees

23

Which type of elements are resistors, lamps, and heating elements examples of?

Resistive

24

What is formed by wire wound around a core?

Coil

25

What is the effect called when a conductor is in a magnetic field and either the field or the conductor moves, an emf (voltage) is induced in the conductor?

Magnetic induction

26

What is the maximum value reached during one alternation of a sine wave called?

Peak Value

27

The average value of a sine wave of voltage or current is the average of all the instantaneous values during one alternation. The average value is equal to what amount of the peak value?

0.636

28

How many times the peak value is the effective value of a sine wave?

0.707