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

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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

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