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AS - 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
Generator
No power source Fixed metal bar w/ coiled wire EMF moves around wire → inductance Magnets rotate to power light bulb
26
"Hot" Conductor
Carries the current through the impedance
27
"Neutral" Conductor
Return the current to the source
28
Shock Hazards
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
Electricity Damage
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
Macroshock
Large amount current | 100-300mA V fib
31
Microshock
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
Grounding
``` 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
Line Isolation Monitor (LIM)
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
Electrosurgical Units
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
Return Plate
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
Return Plate Placement
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
Unipolar
Current returns to unit via dispersive pad
38
Bipolar
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
Anesthesia Concerns
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

AS - N927 Chem/Physics (12 decks)

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