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N927 Chem/Physics > 12 Electricity > Flashcards

12 Electricity Flashcards

1
Q

Current

A 
Electron flow (I)
How much charge (how many electrons) pass through certain point in circuit per unit time
Quantity measured in Amperes
Body current = ion movement
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2
Q

Capacitance

A

Stored charge

Substance ability to store a charge

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3
Q

Inductance

A

How electricity generated

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4
Q

Ohm’s Law

A

I = V / R

Analogous to Q = ΔP/R or BP = CO x SVR

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5
Q

Voltage

A

Electromotive force (EMF) or force that pushes electrons through resistance
Electrical charge potential difference directly proportional to electron flow (electric current)
Driving pressure P1 - P2
Measured in Volts

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6
Q

Resistance

A

Opposition force to electron flow
Flow inversely proportional to resistance
Measured in Ohms

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7
Q

Coulomb

A

Electric charge measure unit
1e¯ = 1.602 x 10^-19
1 Coulomb = 6.24 x 10^18 electrons
1 Coulomb e¯/sec = 1 Amp

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8
Q

Ampere

A

Ampere (Amp) measures current
1 Amp = charge movement carried by 6.24 x 10^18 electrons passing a certain point in 1 second
1 Amp = 1 Coulomb electric charge movement

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9
Q

I = V / R

A 
Current = voltage/resistance
E = I x R
Electromotive force (E) = voltage
E = I x Z
Impedance (Z)
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10
Q

Impedance

A

Represented by Z
Resistance to current flow that changes w/ frequency
Power supply frequency at constant 60Hz
Impedance & resistance are interchangeable

High impedance = low current flow
Low impedance = high current flow

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11
Q

Watt

A

Power unit (work/time)
Joules/second
Electrical power measurement
W = V x I

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12
Q

Joule

A

Watt-second = work = energy
Work = mass x acceleration x distance
kg x m/s^2 x m or 1 Joule

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13
Q

Work

A

Force x distance (displacement)
Force = mass x acceleration
Measured in Joules

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14
Q

Energy

A 
Kinetic = (mass x velocity^2) / 2
Potential = mass x 9.81m/s^2 x height
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15
Q

Power

A

Measured as Watts in electrical circuit

I x V

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16
Q

Conductor

A

Permits e¯ flow

Current = e¯ flow through conductor

17
Q

Non-Conductors

A

Insulators
Tightly bound electrons that do not permit e¯ flow
Ex: glass, rubber, plastic, dry wood, pure water

18
Q

DC

A

Direct current
e¯ flow always in the same direction
Ex: batteries

19
Q

AC

A

Alternating current
e¯ flow reverses direction (oscillates) at regular intervals
Oscillating frequency measured in cycles per second (Hertz or Hz)
Ex: electric company

20
Q

Capacitance

A

Substance ability to store a charge

21
Q

Capacitor

A

Electrical device used to shore electric charge

Basic design - 2 parallel conducting plates separated by insulating layer called dielectric

22
Q

Electromagnetic Field

A

Force field that consists both electric & magnetic components
Resulting from electric charge motion & containing definite amount electromagnetic energy
Electrons flow through wire induce a magnetic field around
When wire coiled repeatedly around an iron core → amplifies the magnetic field
Dual nature r/t electricity & magnetism
- Where there’s an electric current there are also magnetic waves
- Where there are changing magnetic waves there’s an electric current
Able to do work

23
Q

Inductance

A

e¯ flow via wire induce magnetic field surrounding
When wire coiled repeatedly around an iron core this will increase the electromagnetic field to move e¯
Ex: wireless charging

24
Q

Motor

A

Battery source
Metal bar w/ coiled wire
Fixed magnets
Opposing magnetic fields repel e¯ to rotate the metal bar

25
Q

Generator

A

No power source
Fixed metal bar w/ coiled wire
EMF moves around wire → inductance
Magnets rotate to power light bulb

26
Q

“Hot” Conductor

A

Carries the current through the impedance

27
Q

“Neutral” Conductor

A

Return the current to the source

28
Q

Shock Hazards

A

Contact external electricity source
AC or DC current
Source - when person becomes part or completes an electric circuit; must contact the electric circuit at 2 points and there must be voltage source causing current to flow

29
Q

Electricity Damage

A

Current disrupts normal cell electrical function
Or current passing through resistance (body) increases the temperature and can produce a burn
Severity depends on amount of current (Amperes) & contact duration

30
Q

Macroshock

A

Large amount current

100-300mA V fib

31
Q

Microshock

A

Very small amount current
External conductor in direct contact w/ the heart
PA catheter filled w/ NS
100μA (0.1mA) V fib
10μA (0.01mA)
Patient protected by intact ground wire to prevent microshock
Equipment ground wire broken all leakage current able to flow through the catheter → V fib

32
Q

Grounding

A 
Operating room NOT grounded
Equipment = grounded
Grounded 1° electrical company supply
No direct contact b/w power supply & secondary side
OR isolated power supply
33
Q

Line Isolation Monitor (LIM)

A

Continuously checks line 1 & 2 for any current to ground
Any current between line 1 & ground OR line 2 & ground = short circuit
There should be no current b/w line 1 or 2 & ground
Able to used device, but need to replace when possible
Alarm indicates that system no longer totally isolated from ground → short
2mA in older LIM models
5mA in newer LIMs

34
Q

Electrosurgical Units

A

ESU or Bovie
High frequency AC currents
500,000 up to 1 million Hz
Produces up to 3,000V & 400W
Heat generated when current passes through resistance
H = I^2 / A
Heat = current^2 / surface area
Small surface area increases heat to cauterize, cut, & seal off blood vessels
High frequency currents have low tissue penetration & do not excite contractile cells therefore do no cause V fib

35
Q

Return Plate

A

Dispersive electrode w/ large surface area to complete the circuit
Collects & returns energy from the ESU/Bovie
Energy passes through the patient to return place and routed back to the ESU
Large surface area to prevent burns

36
Q

Return Plate Placement

A

Close to operative site
Away from EKG pads
Ensure adequate gel & sufficient skin contact
Do not place over scar tissue, hair, or implants (these prevent good contact w/ the skin and decrease area)

37
Q

Unipolar

A

Current returns to unit via dispersive pad

38
Q

Bipolar

A

Two electrodes - look like forceps
Active & collecting electrode
Collecting completes the circuit back to source
No dispersive pad needed
Less energy than unipolar (just b/w the 2 electrodes)

39
Q

Anesthesia Concerns

A

Radiofrequency waves interfere w/ monitors
ESUs able to reprogram demand pacemakers or cause microshock
Prepare to treat potential dysrhythmias
Inspect return place to ensure applied properly & effective conduction
Disable AICD (automatic implantable cardioverter defibrillator) prior to surgery by placing magnet over

N927 Chem/Physics (12 decks)

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