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ASVAB Practice > Electronics Information > Flashcards

Electronics Information Flashcards

1
Q

A(n) _____ is a subatomic particle that bears no charge.

A

neutron

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2
Q

A neutral atom has the same number of _____ and electrons.

A

protons

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3
Q

Electrons orbit an atom in a set of layers or levels called _____.

A

shells

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4
Q

In an atom, protons have a(n) _____ charge, while electrons have a(n) _____ charge.

A

positive; negative

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5
Q

The outer shell of an atom is known as its _____.

A

valence shell

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6
Q

A watt is defined as _____.

A

one joule per second, or one ampere times one volt

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7
Q

Frequency is usually measured in _____.

A

hertz (Hz)

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8
Q

The conversion of AC to DC is called _____.

A

rectification

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9
Q

What does an electrical ground do?

A

A ground provides a low-resistance path to guide excess electrical energy away from panels and loads, to protect them in the case of lightning or circuit failure.

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10
Q

If an element’s atoms have valence shells that are exactly half full of electrons, that element is a(n) _____.

A

semiconductor

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11
Q

What is the formula for Ohm’s law?

A

V = IR

voltage = current x resistance

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12
Q

What is the formula for electrical power?

A

P = IV

power = current x voltage

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13
Q

What are the two types of transistors?

A

NPN transistor and PNP transistor

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14
Q

Why are transformers especially useful in the transmission of electricity from power plants to residences?

A

It is more efficient to transmit high-voltage electricity, but most household appliances use low-voltage electricity.

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15
Q

When silicon’s crystalline structure is doped with a five-electron element, the silicon crystal becomes a(n) _____ material.

A

N-type (also known as the cathode)

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16
Q

What is a short circuit?

A

A short circuit occurs when a load is bypassed by a conductor, allowing more current to flow through the circuit.

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17
Q

If an element’s atoms have valence shells that are less than half full of electrons, that element is a(n) _____.

A

conductor

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18
Q

Do household electrical outlets in North America use AC or DC current?

A

AC

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19
Q

When a current is passed through a wire coiled around a ferrous material, the result is a(n) _____.

A

electromagnet

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20
Q

If an element’s atoms have valence shells that are more than half full of electrons, that element is a(n) _____.

A

insulator

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21
Q

If multiple loads are connected in a series circuit, how is the overall voltage of the circuit calculated?

A

by adding the voltage drops across the various loads:

total voltage = V1 + V2 + V3…

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22
Q

How can the magnetic field formed by a current-carrying wire be strengthened?

A

by winding the wire into a coil around a ferrous (iron) core

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23
Q

The ____ is a solid-state device that has revolutionized the construction of electronic devices.

A

Transistor

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24
Q

Capacitive reactance is measure in _____.

A

ohms

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25
Q

Resistance can be measured using a device called a(n) _____.

A

ohmmeter

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26
Q

A(n) _____ serves the same function as a fuse but can be used multiple times.

A

circuit breaker

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27
Q

The three major parts of a transistor are ____.

A

the collector, the emitter, and the base

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28
Q

If the resistance provided by a load were to decrease, the current flowing through that circuit would ____.

A

increase

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29
Q

The name for the imaginary flow of positive charge, opposite to the actual flow of electrons, is _____.

A

conventional current

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30
Q

In North America, AC is delivered at _____ Hz.

A

60

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31
Q

Electrical current is measured in _____.

A

amperes (A)

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32
Q

Voltage and current are ____ proportional. (directly / inversely)

A

directly

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33
Q

If one battery’s terminal supplies greater voltage than that of another battery, the first batter terminal has more ____.

A

electrons (or negative charge)

34
Q

A(n) _____ is used to raise or lower current in a circuit.

A

resistor

35
Q

Define load, as it relates to electrical systems.

A

In electricity, a load is a source of resistance that turns electrical energy into some other type of energy.

36
Q

Induction is measured in _____.

A

henries

37
Q

Current and resistance are _____ proportional. (directly / inversely)

A

inversely

38
Q

In a series circuit, does the current vary, alternate, or remain the same throughout the circuit?

A

current remains the same

39
Q

The basic unit of electrical charge is the ____.

A

coulomb (C)

40
Q

What is the equation for frequency?

A

f = 1/T, where f = frequency in Hz and T = the amount of time (in seconds) for one cycle.

41
Q

A circuit with only one path is a(n) ____ circuit.

A

series

42
Q

Why is copper used as a conductor more frequently than is silver or aluminum?

A

Copper is much less expensive than silver and has a lower resistance than does aluminum.

43
Q

Why are parallel circuits usually superior to series circuits?

A

If one path has a break or gap, the circuit will remain closed and current can flow.

44
Q

Current will flow only if it can follow a(n) ____ circuit.

A

closed

45
Q

What is the common term for electrical potential difference or electromotive force?

A

votage

46
Q

What does an ammeter do?

A

An ammeter measures electrical current.

47
Q

Does a battery supply AC or DC current?

A

DC

48
Q

When a P-type semiconductor is joined to an N-type semiconductor, the result is a(n) _____.

A

diode

49
Q

If an AC current is delivered at 20 Hz, what is it that happens 20 times per second in that circuit?

A

The voltage begins at zero, increases to a maximum level, decreases to zero again, switches direction and increases to a maximum level in that direction, and returns to zero again.

50
Q

A(n) ____ resists changes in current flow by applying a voltage that runs against increased current.

A

inductor

51
Q

What is voltage?

A

Voltage is the electric “pressure” produced by a large negative charge.

52
Q

A(n) _____ is constructed of two metal plates and used to store electricity.

A

capacitor (or condenser)

53
Q

Poor conductors have ____ resistance than good conductors.

A

higher

54
Q

What metal is most often used as a conductor in household electrical systems?

A

copper

55
Q

In most home electrical systems, loads are wired in parallel with a fuse wired in ____. (series / parallel)

A

series

56
Q

The process of adding impurities to silicon or germanium in order to improve its usefulness as a semiconductor is called _____.

A

doping

57
Q

Resistance is measured in _____.

A

ohms

58
Q

A(n) _____ is a thin wire that melts when current exceeds a certain amount.

A

fuse

59
Q

Define electrical power.

A

Electrical power is the amount of energy delivered to and used by an electrical circuit.

60
Q

If multiple loads are connected in a series circuit, how is the overall resistance of the circuit calculated?

A

by adding the resistances of the various loads:

Total resistance = R1 + R2 + R3 …

61
Q

A(n) ____ is used to increase or decrease voltage in a circuit.

A

transformer

62
Q

If multiple loads are connected in a parallel circuit, how is the overall resistance of the circuit calculated?

A

by adding the inverse of the resistance of the various loads, and then taking the inverse of the result:

1/total resistance = 1/R1 + 1/R2 + 1/R3…

63
Q

What is the difference between direct current and alternating current?

A

Direct current flows in one direction only; alternating current changes its direction many times a second.

64
Q

What do DC and AC stand for?

A

direct current; alternating current

65
Q

Electrical current flowing through a conductor produces a(n) _____ field.

A

magnetic

66
Q

A load

A. has very low resistance and conducts current throughout the circuit
B. is a device that converts electrical energy into heat, light, or motion
C. is a voltage source
D. switches electrical current off and on

A

B. is a device that converts electrical energy into heat, light, or motion

Loads convert electrical energy into some other form of energy. Examples of loads include heating elements (heat), light bulbs (light), and solenoids (motion).

67
Q

One hertz is equivalent to

A. one cycle per second of any continuous process
B. an acceleration of 1 m/s^2
C. a change in frequency of one cycle per second per second
D. the negative of the period

A

A. one cycle per second of any continuous process

A hertz is a unit of measurement used to express the frequency (cycles per second) of alternating current. One hertz (Hz) is the same as one cycle per second. Choice C is incorrect because it indicates the rate of change in frequency rather than the frequency itself.

68
Q

A (n) _____ is an element that freely conducts electricity.

A. insulator
B. conductor
C. semiconductor
D. molecule

A

B. conductor

A conductor is an element that freely conducts electricity, whereas an insulator does not conduct electricity at all. A semiconductor is neither a good conductor nor insulator, but has some remarkable properties that make it very useful for making electronic components.

69
Q

Which of the following CANNOT describe an “earth ground” in home electricity?

A. a buried conduit
B. a copper rod driven into the ground
C. a device made to protect occupants from electrical shock
D. a device for measuring electrical resistance

A

D. a device for measuring electrical resistance

An earth ground is found outside a building, and normally utilizes conductors such as conduit or pipe that is already in the ground. All of the ground connectors in a residential wiring system will be attached to an earth ground, which is used to “funnel” away stray electricity in appliances and prevent it from causing electrical shock. A ground does not measure resistance.

70
Q

Electron flow theory states that

A. electrons flow best through liquids
B. electrons flow from area of excess negative charge to areas of less negative charge
C. electrons flow from areas of excess positive charge to areas of less positive charge
D. electrons can only flow from one area to another if there is no resistance

A

B. electrons flow from areas of excess negative charge to areas of less negative charge

In electron flow theory, electrons flow away from areas of excess negative charge to those with a deficiency of negative charge. When a conductor is connected across the terminals of a battery, the electrons in the conductor will be forced away from the negative terminal of the battery and toward the positive terminal. Therefore C is clearly wrong. Electrons can flow through solids and gases as well as liquids, so A is incorrect. While resistance can reduce the flow of electrons, it does not necessarily stop the flow completely, so D is incorrect.

71
Q

The “electrical pressure” that causes electrons to flow in one direction through a conducting path is a result of

A. a voltage
B. a difference in resistance
C. parallel paths
D. a wire moving downhill

A

A. voltage

Electrical pressure is known as voltage, and it is measured in volts (symbolized by the letter V).

72
Q

Under a constant voltage, increasing resistance results in current flow

A. dropping
B. rising
C. staying the same
D. changing direction

A

A. dropping

Ohm’s law tells us that V = I x R. If voltage stays constant, and resistance R rises, current I would have to drop.

73
Q

Increasing the voltage in a circuit and keeping resistance the same will result in

A. increased current flow
B. decreased current flow
C. current flow staying the same
D. zero current flow

A

A. increased current flow

Ohm’s law tells us the R = V / I. If resistance R stays constant, and voltage V rises, current I will also have to increase.

74
Q

Several loads in series have different resistances. Given that the same current flows through each of them, what relationship does Ohm’s law predict between resistance and voltage drop?

A. Larger voltage drops occur across loads with greater resistances.
B. Smaller voltage drops occur across loads with greater resistances.
C. Larger voltage drops occur across loads with lesser resistances.
D. An equal voltage drop occurs across each load in series, independent of resistance.

A

A. larger voltage drops occur across loads with greater resistances.

Since V = I x R, and the current is the same across all resistors, in increase in resistance must result in an increase in the voltage drop.

75
Q

Capacitive reactance decreases as electrical frequency

A. decreases
B. increases
C. varies
D. gets closer to DC

A

B. increases

A capacitor is made to block DC (direct current), but allow AC (alternating current) to flow. Capacitive reactance is a capacitor’s “opposition” to the flow of current, and this tends to diminish as the frequency of alternating current increases.

76
Q

Which of the following CANNOT be used to make the magnetic field in a coil of wire stronger?

A. increasing the number of turns of wire in the coil
B. increasing the current flowing through the coil
C. inserting an iron core into the middle of the coil
D. inserting a dielectric between each coil

A

D. inserting a dielectric between each coil

An electromagnet’s magnetic field becomes stronger when more turns of wire are added to it, more current is passed through the coil, or an iron core is placed in the middle of the coil.

77
Q

Whenever current passes through a resistance, ____ is most often generated.

A. voltage
B. capacitance
C. heat
D. light

A

C. heat

When current passes through a resistance, a voltage drop will take place. This represents an energy loss, and this energy is normally dissipated in the form of heat.

78
Q

The formula for Ohm’s Law is

A. V = I x R
B. V = I - R
C. V = I + R
D. V = I / R

A

A. V = I x R

Ohm’s law states that voltage in volts is equal to the current in amperes multiplied by the resistance in ohms, or V = I x R. V represents voltage, and I represents current. Current is the rate of flow of electrons, or the intensity of the flow. (Specifically, I is the rate of charge flow.) Finally, R represents resistance.

79
Q

If current is able to pass through a diode, the diode must be

A. reverse-biased
B. forward-biased
C. open
D. grounded

A

B. forward-biased

When current flows freely through a diode, this is known as “forward bias.” If the orientation of the diode is such that it blocks current flow, that would be reverse bias. Open and grounded are irrelevant to the question that was asked.

80
Q

Transistors are turned on and off by voltages applied to their

A. collector
B. emitter
C. base
D. cathode

A

C. base

A transistor has three connections: the base, the emitter, and the collector. The transistor is switched off and on by voltages applied to its base. When a voltage appears across the base-emitter junction, the transistor switches on and allows current to flow between the collector and emitter.

ASVAB Practice (11 decks)

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