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KLowe Chemistry And Physics Larmon > Electricity And Electrical Safety > Flashcards

Electricity And Electrical Safety Flashcards

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1
Q

What is electricity?

A

Effects produced by moving charges

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2
Q

What are two kinds of charge?

A
  • positive

- negative

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3
Q

What is the SI unit of charge?

A

Coulomb (C)

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4
Q

Charge of 1 electron

A

-1.6 x 10 ^ -19 C

“-e”

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5
Q

Charge of 1 proton

A

+ 1.6 x 10 ^ -19 C

“e”

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6
Q

Opposite charges

A

Attract

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7
Q

Like charges

A

Repel

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8
Q

Coulomb’s Law

A

Like charges repel, opposite charges attract

Law gives the magnitude of the electrostatic force of attraction or repulsion

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9
Q

What is electric current?

A

The amount of charge flowing per unit time

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10
Q

Conductors

A

Materials in which charges can easily move

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11
Q

___ are good electrical conductors

A

Metals

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12
Q

Most ___ are nonmetals and generally are not good conductors

A

Insulators (except for graphite)

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13
Q

To be a good conductor, electrons must be able to…

A

Move easily from one atom to the next

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14
Q

Electrical conductors are made of atoms that ___

A

Do not hold onto electrons tightly

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15
Q

Metals have electron shells that are mostly ___

A

Empty—good conductors

I.e.: Copper only has one electron in its fourth energy level

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16
Q

In the molecular orbital (MO) approach to bonding, atomic orbitals from individual atoms are ___ together to form molecular orbitals that extend over the entire molecule

A

Added

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17
Q

The MO approach to bonding results in a large collection (or band) of MOs that is only ___ filled; thus, there is room to ___ into the “molecule” with very little energy

A

Partially filled; room to accept new electrons

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18
Q

Electrical conductors allow electrons to pass through their conduction bands with very little effort, but not ___ effort

A

Zero

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19
Q

The energy required to push electrons through a material is a measure of the ___ of the material to the passage of current

A

Resistance

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20
Q

Resistance is measured in ___

A

Ohms

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21
Q

Conductance is the reciprocal of ___

A

Resistance

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22
Q

Conductance is measured in ___ or ___

A

Mhos or Siemens (S)

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23
Q

What is the electric circuit?

A

The closed path through which a charge flows

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24
Q

Direct current (DC) circuit

A

An electrical circuit in which the current flows in one direction only

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25
Q

Alternating current (AC) circuit

A

An electrical circuit in which the current reverses its direction in a periodic fashion

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26
Q

DC = electron flow is always ___

A

In the same direction

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27
Q

AC = electron flow ___ at regular intervals

A

Reverses direction

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28
Q

Short circuit

A

A situation in a circuit where the normal resistance of the circuit is bypassed by a low resistance path, resulting in a large current

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29
Q

If the current from a short circuit is not limited by a fuse or circuit breaker, the resulting heat from the high current can lead to a ___

A

Fire

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30
Q

Series circuits—when batteries or resistors are connected in a series, the voltages and resistances are ___

A

Added

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31
Q

Parallel circuits—when resistors are connected in parallel, current flows through each resistor ___ of the other

A

Independently

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32
Q

Electrical power is the product of ___ and ___

A

Volts and amps

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33
Q

Power is measured in ___

A

Watts

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34
Q

Power is the ___

A

Rate of using energy

35
Q

Power =

A

Energy/time

36
Q

Energy =

A

Power x time

37
Q

Two types of electrical shocks:

A
  • Macroshock

- Microshock

38
Q

Macroshock

A

Large amounts of current conducted through a patient’s skin or other tissues

The extent of injury will depend on the amount of current and the duration of the exposure

39
Q

Microshock

A

The delivery of small amounts of current directly to the heart

Very small currents (< 50 micro amps) can produce ventricular fibrillation!

40
Q

What is on a piece of equipment that provides a low-resistance pathway for leakage current and constitutes the major source of protection against Microshock in the electrically susceptible patient?

A

The ground wire

41
Q

Never simultaneously touch an electrical device and a ___ or ___

A

Saline-filled CVP catheter or external pacing wires (wear rubber gloves)

42
Q

Polarized plugs

A

Plugs with one narrow prong and one wide prong

43
Q

Polarized plugs ensure that the plug may only be inserted into the outlet in ___

A

One orientations

44
Q

Narrow prong is for ___

A

High potential

45
Q

Wide prong is for ___

A

Low potential

46
Q

Electrical devices are designed so that the casing is connected to the ___ and thus at low potential

A

Wide prong

47
Q

Three-pronged grounded plug

A

Plug that contains a rounded third prong that is connected to ground when plugged into a three-pronged receptacle

48
Q

The third prong is wired directly to the ___

A

Casing of the electrical device

49
Q

If for some reason a high-potential wire comes into contact with the case, the current will flow directly through the ___ instead of through your body

A

Third prong

50
Q

Ground fault circuit interrupter (GFCI)

A

Immediately (within 1 ms) disrupt the flow of current in the circuit if a change in current is detected

51
Q

GFCIs are used in circuits near ___

A

Water sources

52
Q

What is a disadvantage of using a GFCI in the operating room?

A

It interrupts the power without warning—the defective piece of equipment can no longer be used, which might be a problem if it were necessary for life support

53
Q

Modern electrical circuits are typically ___

A

Grounded (intended as a safety feature but can pose a risk to humans)

54
Q

How can shock to a human occur at ground potential?

A

Humans who are at ground potential because of what they are touching have to only touch a single object to complete a circuit, resulting in shock

55
Q

To further decrease the risk of electrical shock in operating rooms, electrical systems are isolated from the ___ through the use of isolation transformers

A

Grounded electrical supply

56
Q

Isolation transformers rely on ___ to transfer a current from the grounded electrical system to an ungrounded secondary system without the two systems ___

A

magnetic inductance; WITHOUT the two systems physically contacting each other

57
Q

Ungrounded systems in the operating room prevent ___

A

Accidental shocks resulting from simply touching a single live wire

58
Q

If live wires make contact with a ground, the ungrounded system now becomes a ___—we thus say that a ___ has occurred, resulting in a ___

A

Grounded system—a fault has occurred, resulting in a grounded system

59
Q

A fault can occur if a live wire touches a ___

A

Casing on a piece of equipment

60
Q

A second fault can result in a ___

A

Shock

61
Q

What is a line isolation monitor?

A

A device that alarms when a fault in an ungrounded system occurs

62
Q

Line isolation monitors are located between ___ and ___ so that the impedance to current flow can be measured

A

Live wires and a ground

63
Q

If contact is made between a live wire and a ground, current will flow, resulting in ___

A

An alarm

64
Q

The alarm set point for a line isolation monitor is usually between ___ and ___ mA

A

2 and 5 mA

65
Q

If the gauge on the line isolation monitor reads between 2 and 5 mA, there is probably ___ plugged into the circuit

A

Too much electrical equipment

66
Q

If the gauge is reading > 5 mA, it is likely that a ___ is present in the operating room

A

Faulty piece of equipment

Equipment may be identified by unplugging each piece of equipment until the alarm is silenced

If faulty piece of equipment is not essential, it should be removed from the operating room

67
Q

The line isolation monitor is not designed to provide protection from ___

A

Microshock

68
Q

Potential hazards in the operating room include ___

A

Electrical shock to the patient and operating room personnel

69
Q

All healthcare facilities are required to have ___

A

A source of emergency power (electrical generators, battery-operated light sources including laryngoscopes, etc.)

70
Q

Objective of electrical safety is to make it difficult for ___

A

Electrical current to pass through people

71
Q

Isolation transformer is used to convert ___ power to ___ power

A

Grounded power to ungrounded power

72
Q

Line isolation monitor warns that ___ has been lost in the event that a defective piece of equipment has been plugged into one of the isolated circuit outlets

A

Isolation of the power from the ground has been lost

73
Q

Equipment that is plugged into the isolated power system has an equipment ___ that provides an alternative low-resistance pathway

A

Ground wire

74
Q

Electrosurgery (ESU) operates by generating ___

A

High-frequency currents (radiofrequency range)

75
Q

ESU— ___ is generated whenever a current passes through resistance

A

Heat

76
Q

High-frequency currents have a low ___ and do not excite ___

A

Low tissue penetration; do not excite contractile cells

77
Q

High-frequency electrical energy generated by the ESU interferes with signals from ___

A

Physiologic monitors

78
Q

How can the ESU be safely operated?

A

Application of a large surface area dispersive electrode to the patient (allows energy to be routed from the unit, through the patient, and back to the unit)

79
Q

ESU—the area of the return plate is ___

A

Large

80
Q

ESU—the current density is ___

A

Low

81
Q

ESU—no harmful ___ or ___ occurs

A

Heat or tissue destruction occurs

82
Q

If the return plate is improperly applied to the patient or if the cord connecting the return plate to the ESU is broken, the high-frequency electrical current will ___

A

Seek an alternate return path

83
Q

The power supply is isolated from the ground to protect the patient from ___ by eliminating ___

A

Burns, eliminating alternate return pathways

84
Q

The most important factor in preventing patient burns from the ESU is ___

A

Proper application of your return plate!

KLowe Chemistry And Physics Larmon (11 decks)

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