Electricity Flashcards

1
Q

in electricity, current is

A

the movement of electrons

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2
Q

electric current

A

how much charge (how many electrons) pass a certain point in a circuit per unit time

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3
Q

each electron has a charge of

A

1.60217733 x10^-19 coulombs

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4
Q

a coulomb

A

unit of measure of electric charge

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5
Q

6.24 x10^18 electrons carry charge of

A

1 coulomb

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6
Q

movement of 1 coulomb of charge in 1 second is

A

1 ampere (amp)

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7
Q

1 amp of current =

A

1 coulomb/sec

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8
Q

the flow of electrons (electric current) is inversely proportional to

A

resistance

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9
Q

electromotive force

A

potential difference of electric charges from one area to the next

(pushes the electrons through the resistance)

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10
Q

the greater the potential difference

A

the greater the push of electrons through a resistance and the greater the flow of electrons

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11
Q

potential difference is directly proportional to

A

the flow of electrons (electric current)

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12
Q

equation for the relation of flow of electrons, potential difference, and resistance

A
I = V/R
I = current, V = voltage, R = resistance
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13
Q

the potential difference is measured in

A

Volts

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14
Q

current is quantity of electrons measured in

A

amperes (amps)

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15
Q

resistance is measured in

A

Ohms

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16
Q

current can only flow if it gets

A

pushed

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17
Q

2 forms of electrical current flow thru a conductor

A
alternating current (Volts-AC)
direct current (Volts-DC)
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18
Q

Impedance

A

Z

consist of resistance plus other factors that effect electron flow

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19
Q

examples of EMF

A

static electricity, lightening

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20
Q

the product of voltage and current

A

watt (unit of power)

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21
Q

amount of electrical work done measured in

A

watt-sec which = joules

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22
Q

energy produced by defibrillator is measured in

A

watt-sec

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23
Q

energy consumption in a home is measured in

A

kilowatt-hours

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24
Q

a closed loop must have

A

completed circuit with driving pressure (V), to force a current (I), to flow thru a resistance (R)

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25
Q

conductor

A

any substance that permits a flow of electrons (loosely attached and easily lost electrons)

26
Q

current flow follows a gradient from

A

high voltage to low voltage

seeks path of least resistance

27
Q

nonconductors or insulators

A

have tightly bound electrons which do not permit electron flow (glass, rubber, plastic, dry wood, pure water)

28
Q

in direct current the electron flow is

A

always in the same direction

29
Q

in alternating current the electron flow

A

reverses direction at regular intervals, measured in Hz (cycles per second)

30
Q

when dealing with AC circuits the flow of current is opposed by

A

impedance

31
Q

inductance generates

A

an electromagnetic field which creates increased resistance

32
Q

capacitance generates

A

capacitance current in electrical circuit that creates a decrease resistance in the circuit

33
Q

capacitance is

A

a measure of substance’s ability to store a charge

34
Q

in DC circuit the capacitor plates are

A

charged by a voltage source and the flow of current is momentary

35
Q

in AC circuit the capacitor plates

A

permits current of flow even when the circuit is not completed by a resistance

36
Q

stray capacitance

A

power cord, consists of 2 insulated wires next to each other will generate capacitance just being plugged in

37
Q

as frequency increases

A

impedance to electron flow will decrease

38
Q

electrosurgical units use

A

high frequency currents so they have low impedance

39
Q

a basic capacitor consists of

A

2 parallel conducting plates separated by an insulating layer (dielectric)

40
Q

a capacitor is an electrical device used for

A

storing electric charge

41
Q

what makes substances like iron, cobalt, and nickel magnetic

A

most of the electrons spin in the same direction

42
Q

when electricity runs through a coil of wire

A

it produces a magnetic field

43
Q

in an AC circuit, inductance can

A

electromagnetically generate an opposing electromotive force in a nearby wire

44
Q

bending a wire into a coil

A

amplifies the magnetic field

45
Q

the hot conductor

A

carries the current thru the impedance

46
Q

the neutral conductor

A

returns the current to the source

47
Q

the amount of current flowing thru the conductors depends on

A

the amount of impedance

48
Q

high impedance

A

low current flow

49
Q

low impedance

A

high current flow

50
Q

a short circuit or fault is

A

a condition in which there is zero impedance with a high current flow

51
Q

electric shock can occur

A

by contacting AC or DC current

52
Q

electrical shock occurs when

A

a person becomes part of or completes an electric circuit

53
Q

for a shock to occur

A

must contact the electric circuit at 2 points and a voltage source causing current to flow

54
Q

in the OR there are 2 categories of electric shock

A

macroshock - large amount >1mA

microshock - small amount <1mA

55
Q

a PA catheter with conducting fluid can

A

send current directly to the heart

56
Q

how many mA can cause vfib

A

100-300mA in macroshock

100mmA in microshock

57
Q

person contacts a 120V circuit with skin resistance of 1000 vs 100,000 ohms

A
120V/1000ohms = 0.12 amps = 120mAmps
120V/100,000ohms = .0012 = 1.2 mAmps
58
Q

power is ___ in the OR

A

ungrounded

59
Q

electrical equipment in the OR should be ___

A

always grounded

60
Q

grounding of power and equipment provides

A

low resistance pathway for current during faults