What are the Two Types of Electrical Charges
Positively Charged - More protons than electrons
Negatively Charged - Less protons than electrons
What is the Fundamental Principle of Charge Interaction?
Opposite charges attract
Same charges repel
What is Electrical Current?
Amount of Charge flowing per unit time
1 ampere = 1 Coulomb charge per second
What are Electrical Conductors?
Materials where charges easily move
Atoms that dont hold on tightly to electrons
Outer shell mostly empty
What are Electrical Insulators?
Nonmetals that are not good conductors
What is the Molecular Orbital approach to bonding?
Individual Atomic Orbitals are added together to form a molecular orbital extending over the entire molecule
What is Electrical Resistance?
Energy needed to push electrons through a material
Resistance (R) measured in ohms (Ω)
Electrical Potential = Current x Resistance
V = IR
Reciprocal of Resistance measured in mhos or siemens
G = 1/R
What is an Electric Circuit?
The closed Path through which a charge flows
What is a Direct Current Circuit?
A circuit where the charge flows in one direction
What is an Alternating Current Circuit?
A circuit where the current reverses its direction periodically
What is a Short Circuit?
When the normal resistance in a circuit is bypassed by a low resistance path resulting in a Large Current
If there is no fuse or circuit breaker = Fire
How is the Total Resistance found in a Series Circuit
How is the Total Resistance found in Parallel Circuits?
Current flows thru each resistor indepently of each other
1/Rtotal = 1/R1 + 1R2 + 1/R3...
What unit is Electrical Power measured?
Electrical Power = Volts x Amps
Measured in Watts
1 watt = 1 V x A
What is the difference between Power & Energy?
Power = Energy/Time
Energy = Power x Time
(We Pay For Energy)
What are the different types of Electrical Shocks?
Macroshock - large amt. of current conductred thru pts skin or other tissues
Microshock - small amt. of current directly to the heart.
How big of a microshock will cause Ventricular Fibrillation?
< 50 µA can cause V Fib
What provides a low-resistance pathway for current leakage and is the major source of protection against microshock?
The Ground Wire
Never touch an electric device & a saline-filled CVP catheter or pacing wire at the same time
How do Patient Monitors protect the patient from Microshock?
Isolates all direct patient connections from the power supply
How are modern plugs made to be safer from Shock?
Polarized Plugs - one narrow and one wide prong
Wide Prong = Low Potential
What is the Third Prong of a Plug and how does it work?
The Ground Prong - Wired directly to the casing of electrical device
What is the Ground Fault Circuit Interrupter (GFCI)?
Used in circuits near water.
Immediately disrupts flow of current if a change in current is detected
What is a disadvantage of using a Ground Fault Circuit Interrupter (GFCI) in an OR?
Power can be stopped w/o warning
Defective Equipment can longer be used
How can Ground Systems still pose a risk?
People who are at Ground Potential just need to touch a single object to complete a circuit shock
How do Modern ORs decrease the risk of Electrical Shock?
Electric Systems are isolated from the Grounded Electrical Supply through Isolation Transformers
How do Isolation Transformers work?
Rely on Magnetic Inductance to transfer current b/t grounded & ungrounded systems without the two actually touching
Do you want Grounded or Ungrounded systems in the OR?
What is considered an Electrical "Fault"?
When a Live wire touches the ground or equipment casing causing the ungrounded system to become grounded
A Second Fault can cause a Shock