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H - Electronics > H - Electronics > Flashcards

H - Electronics Flashcards

1
Q

what is an atom, and what is it made up of

A

an atom is a fundamental piece of matter, and consists of protons, neutrons and electrons

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2
Q

how are the following charged:

neutrons, electrons and protons

A

neutrons are neutrally charged,

electrons are negatively charged,

protons are positively charged

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3
Q

how would you describe electricity

A

a form of energy resulting from the existence of particles either statically as an accumulation of charge or dynamically as a current.

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4
Q

what is voltage

A

the potential electrical difference between 2 points in circuit, or one point and a ground

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5
Q

what is charge

A

the concentration of electrons at a given circuit point

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6
Q

what is current

A

the rate of flow of electrons, and describes the number of electrons that pass a point per second

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7
Q

what is the difference between conventional and actual current flow

A

electrons flow from negative to positive points in a circuit in actuality, due to their negative charge, but this is the other way round in conventional current flow.

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8
Q

define AC

A

alternating current, it implies flow of electrons in alternating directions

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9
Q

define DC

A

implies electrons flow in one direction only

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10
Q

what does RMS stand for

A

Root Means Square

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11
Q

define resistance of a circuit

A

resistance is the opposition to current flow

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12
Q

what do conductors do

A

they are materials that allow electrons to flow easily

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13
Q

what do insulators do

A

they offer high resistance to current flow

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14
Q

what do semi conductors do

A

they allow current flow only under specific conditions

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15
Q

define ohms law

A

current is directly proportional to voltage and indirectly proportional to resistance

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16
Q

what is the definition of work

A

it refers to an activity involving force and movement in the direction of force

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17
Q

define energy, and what it is measured in

A

energy is the capacity for doing work, must have energy to accomplish work. Energy is measured in Joules

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18
Q

what do transformers do

A

they bring the voltage up or down, and they only work with AC

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19
Q

what does a transducer do

A

converts one type of energy into another one

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20
Q

define kirchoffs law

A

in circuits in series: kirchoffs law states that voltage is shared between resistors, and current remains the same

in circuits in parallel: kirchoffs law states that the voltage across resistors remains the same, and the current is split

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21
Q

what are capacitors

A

the terminal electronic component that stores electrical energy in an electric field

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22
Q

what is a capacitors time constant

A

the time constant determines the time it takes the capacitor to charge

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23
Q

what is reactance

A

it is the opposition to a circuit element to a change in current or voltage, due to that elements inductance or capacitance. It is a frequency dependent opposition

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24
Q

what are inductors, and what does inductance do

A

An inductor is simply a coil of wire. When current passes through the coil, an electrical field is generated. The field has been “induced.” The bigger the coil or the greater the number of turns, the greater the induced field. This phenomenon is called “inductance.”

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25
Q

what is impedance

A

the effective resistance of an electric circuit or component to alternating current arising from the combined effects of resistance and reactance

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26
Q

what is circuit ground

A

an electrical connection to the earth, a common return path in circuits

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27
Q

what is ground loop

A

it occurs when 2 points in a circuit have a potential difference between them, and is a cause of noise and hum

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28
Q

what are ground loop transformers

A

they break the connection of a dc circuit between components while passing the different signal of the line

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29
Q

what is the difference between balanced and unbalanced audio

A

unbalanced cables carry a ground wire, balanced cables carry 2 copies of the same signal which are reversed and phase flipped.

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30
Q

what is a ground isolator

A

it disrupts the noise in ground loops

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31
Q

what is a CR circuit

A

a capacitor and a resistor in circuit series

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32
Q

what is the output across the capacitor in a CR circuit

A

a low pass filter

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33
Q

what is the output across the resistor in a CR circuit

A

a high pass filter

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34
Q

what is an LR circuit

A

an inductor and a resistor in circuit series

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35
Q

what is the output across the inductor in a LR circuit

A

a high pass filter

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36
Q

what is the output across the resistor in an LR circuit

A

a low pass filter

37
Q

what is an LCR circuit

A

a capacitor/ inductor/ resistor in series circuit

38
Q

what happens to the low frequencies across the capacitor in an LCR circuit

A

the low frequencies drop across it, and create a low pass filter

39
Q

what happens to the high frequencies across the inductor in an LCR circuit

A

the high frequencies will drop across it, and create a high pass filter

40
Q

what happens to the mid frequencies across the resistor in an LCR circuit

A

the mid frequencies will drop across it, and create a band pass filter

41
Q

how much is the cutoff frequency attenuated by in dB

A

3 dB

42
Q

what are diodes

A

a diode is a semi conductor device, as they normally only allow current to travel in one direction

43
Q

what are transistors

A

a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit.

44
Q

What is a capacitor?

A

a device used to store an electric charge, made of one or more pairs of conductors separated by an insulator (dielectric)

45
Q

How does a capacitor store charge?

A

when connected to an electric circuit one plate attracts electrons and one repels them, leading to a buildup of positive charge on one plate and an equal negative charge on the other.

46
Q

What does the frequency of AC reflect?

A

how many times in a second the current changes direction

47
Q

name examples of conductors

A

silver

copper

gold

aluminium

zinc

nickel

brass

48
Q

name examples of semi-conductors

A

carbon

silicon

germanium

49
Q

Name examples of insulators

A

rubber

plastic

ceramics

air

dry paper

pure water

wood

50
Q

What is resistance? What unit of measurement is used?

A

opposition to current flow

measured in ohms (Ω)

51
Q

What is a semi-conductor?

A

a substance that allows current to flow only under specific conditions

can have very useful properies like…

allowing current to flow more easily in one direction than the other
showing variable resistance, sensitivity to light or heat

52
Q

What type of current do we use in homes and other buildings?

A

AC

53
Q

What kind of electricity is used by most of our devices?

A

DC

54
Q

Define power.

What is the unit of measurement used?

A

DEF: the rate of work done over time or the rate of using energy.

measured in watts (W)

55
Q

Define ‘joule’

A

DEF:

the SI unit of work or energy, equal to the work done by a force of one newton when it’s point of application moves one meter in the direction of action of the force, equivalent to one 3600th of a watt-hour

56
Q

How many joules are in 1 Watt?

A

1 W = 1 joule per second

57
Q

What determines the amount of charge that can be held by a capacitor?

A

size of plates, distance between them and the material used for the dielectric

58
Q

Capacitance is measured in ________.

A

farads (F)

59
Q

what is the SI unit of voltage and what is it measured in

A

voltage (V) is measured in Volts (V)

60
Q

what is the SI unit of charge and what is it measured in

A

charge (Q) is measured in coulombs (C)

61
Q

what is the SI unit of current and what is it measured in

A

current (I) is measured in amperes (A)

62
Q

what does RMS stand for

A

root means squared

63
Q

what is the SI unit of resistance and what is it measured in

A

resistance (R) is measured in ohms (Ω)

64
Q

what is the SI unit of energy and what is it measured in

A

energy (W) is measured in Joules (J)

65
Q

what is the SI unit of power and what is it measured in

A

power (P) is measured in Watts (W)

66
Q

what is the SI unit of capacitance and what is it measured in

A

capacitance (C) is measured in Farads (F)

67
Q

what is the SI unit of time constant

A

τ (tau)

68
Q

what is the SI unit of reactance and what is it measured in

A

reactance (x) is measured in ohms (Ω)

69
Q

what is the SI unit of inductors and what is it measured in

A

inductors (L) is measured in henrys (H)

70
Q

what is the SI unit of impedance and what is it measured in

A

impedance (Z) is measured in ohms (Ω)

71
Q

what does EMF stand for

A

Electromotive Force, and causes electrons to flow

72
Q

one coloumb is the combined charge of how many electrons

A

6.241 x 10 to the power of 18

73
Q

what does ohms law state

A

current is directly proportional to voltage and indirectly proportional to resistance

74
Q

what does one joule correspond to

A

the amount of force needed to accelerate a mass of 1KG, 1 meter per second, squared

75
Q

what does the power of one watt corrospond to

A

the conversion of 1 joule of energy per second

76
Q

what factors effect the charge that a capacitor can hold

A

its size, distance between plates and the material used

77
Q

the more a capacitor is charged, the higher the….

A

opposition to current flow

78
Q

what happens when a capacitor is connected to an AC supply, with a high frequency

A

if the frequency is high enough, the capacitor will not have time to charge in either direction, and the opposition to current flow will be low

79
Q

what happens when a capacitor is connected to an AC supply, with a low frequency

A

the capacitor will have enough time to charge in one direction, and the opposition to current flow will be high

80
Q

capacitors are frequency dependent in their opposition to current flow, this opposition is know as….

A

reactance

81
Q

what are inductors

A

An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a coil around a core.

82
Q

what does a current carrying conductor induce

A

a magnetic field around itself

83
Q

what is inductive reactance

A

Inductive reactance is the name given to the opposition to a changing current flow. This impedance is measured in ohms, just like resistance.

84
Q

what is the rule of thumb for impedance briding

A

low output (source) should meet high input (load) impedances

85
Q

what is impedance matching

A

when source output (source) equals source input (load), and maximum power is transferred.

86
Q

what is bridged impedance matching

A

when the load impedance is equal to or greater than 10 times the output impedance

87
Q

what do DI boxes do in terms of impedence

A

they lower the output impedance of devices such as electric guitars, bases etc.

88
Q

what do transformers do

A

they make it possible to step up or down voltage and current

H - Electronics (1 decks)

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