Basic Principles of Basic Principles of Electricity Electricity Jennifer L. Doherty-Restrepo, MS, LAT, ATC FIU Entry-Level ATEP PET 4995: Therapeutic Modalities
Basic Principles of Basic Principles of ElectricityElectricity
Jennifer L. Doherty-Restrepo, MS, LAT, ATCFIU Entry-Level ATEPPET 4995: Therapeutic Modalities
Electromagnetic SpectrumElectromagnetic Spectrum
Electrical Stimulating CurrentsElectrical Stimulating CurrentsCommercial Radio and TelevisionCommercial Radio and Television
Shortwave DiathermyShortwave DiathermyMicrowave DiathermyMicrowave Diathermy
InfrareInfrareddLASERLASER
Visible LightVisible Light
UltravioletUltraviolet
Ionizing RadiationIonizing Radiation
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LongestLongestWavelengthWavelength
ShortestShortestWavelengthWavelength
LowestLowestFrequencyFrequency
HighestHighestFrequencyFrequency
ElectronsElectrons
Particles of matter possessing a ________ charge and a small ________
Net movement of electrons is an ________ ________
Electrons will move from ________ to ________ energy levels• Establishes an electrical ________
Electrical Potential Electrical Potential DifferenceDifference
Difference in ________ of electrons between two points
Electrons will not move unless a ________ difference exists
AmpereAmpere
Unit of measure which indicates _____ at which electrons flow• 1 _____ = movement of 1 coulomb or
6.25x1018 electrons /sec Current flow is typically described
as:• ________ (1/1000 of an amp), or • ________ (1/1,000,000 or an amp)
VoltVolt
Creates the electrical potential ________
The __________ ________ which must be applied to create flow of electrons
Commercial current (wall outlets) is either ________ or ________
ConductorsConductors
Materials that permit ______ movement of electrons
Composed of large numbers of ________ electrons
Offer ________ resistance to current flow Good conductors:
• Metals (copper, gold, silver, aluminum)• Electrolyte solutions
InsulatorsInsulators
Materials that ______ the flow of electrons
Contain ________ free electrons Insulator materials:
• Air, • Wood, and • Glass
Resistance = Electrical Resistance = Electrical ImpedanceImpedance
________ to flow of electrical current Measured in ________
• Unit of measure indicating resistance to current flow
Ohm’s law: current flow is ________ proportional to ________ and ________ proportional to ________ • Current flow = Voltage
Resistance
WattWatt
Measure of electrical ________ Electrical ______ is the product of
______ (electromotive force) and the amount of current flowing• Watts = volts X amps
Indicates the ________ at which electrical power is being used
Electrotherapeutic Electrotherapeutic CurrentsCurrents
3 types of currents capable of producing specific physiological effects• ________• ________ • ________
Therapeutic effects of will be discussed in Chapter 8
Direct Current (DC)Direct Current (DC)
Uniterrupted, uniderectional flow of electrons in the ________ direction
Also called ________ currents Sometimes called ________ currents
Alternating Current (AC)Alternating Current (AC)
Continuous flow of electrons changes direction• Always flows from ________ to ________ pole until
polarity is reversed Also called ________ currents
Pulsitile (Polyphasic) Pulsitile (Polyphasic) CurrentsCurrents
________ electrical current that contains __ or more grouped phases in a single pulse
Also called ________ and ________ currents
Electrical GeneratorsElectrical Generators
Transcutaneous Electrical Nerve Stimulators (TENS)• Stimulates ________ ________
Neuromuscular Electrical Stimulator (NMES) = Electrical Muscle Stimulator (EMS)• Stimulates ________
Microcurrent Electrical Nerve Stimulators (MENS) = Low Intensity Stimulators (LIS)• Assists the ________ ________
All Are Transcutaneous Electrical Stimulators!All Are Transcutaneous Electrical Stimulators!
Electrotherapeutic Electrotherapeutic CurrentsCurrents
No relationship between type of current used to power the generator and the type of current transmitted to patient
Generators may be powered by AC or DC• Batteries = DC between 1.5 - 9 V• Wall outlet = AC at 120 or 220V at 60 Hz
Waveform or PulseWaveform or Pulse
Pulse = ________ ________
Phases (duration) Interpulse interval Direction (polarity) Amplitude Rate of ________ Rate of ________
• Accommodation
Symmetrical WaveformsSymmetrical Waveforms
Sine Square Triangular Spiked
____ and _____ of each phase is identical
Symmetrical WaveformsSymmetrical Waveforms
Twin peaked triangular waveform• Found on most high
volt generators
Asymmetric WaveformsAsymmetric Waveforms
________ • No longer used No longer used • Effects were Effects were
similar to DC similar to DC pulsed wavepulsed wave
________ • SawtoothSawtooth• Used to stimulate Used to stimulate
denervated muscledenervated muscle
Current ModulationCurrent Modulation
(A) Continuous (B) Interrupted (C) Burst
• Packets (envelopes)
• Pulse trains• Beats
(D) Ramped (Surge)
Pulse AmplitudePulse Amplitude
Amplitude = current intensity = voltage ______ ______ = amount of current flowing
per unit time• Determined by interpulse interval or current
duration Measured in ________ or ________
Pulse DurationPulse Duration
Length of ________ current is flowing Monophasic current:
• ______ ______ = ______ ______ Biphasic current:
• Pulse duration is determined by the combined ______ durations
Polyphasic current:• The combined pulse duration and interpulse
interval is the ______ ______
Pulse Frequency Pulse Frequency
Number of Number of ______ or or ______ per per secondsecond• Measured as pulses per second (PPS)Measured as pulses per second (PPS)
Individual pulse = rise and fall in Individual pulse = rise and fall in amplitudeamplitude
As frequency As frequency ___________, , amplitude amplitude ________ and and ________ more rapidlymore rapidly
Pulse Frequency Pulse Frequency
Effects the type of muscle contraction• Pulse rate of less than ___ pps = muscle twitch• Pulse rate equal to or greater than ___ pps =
tetany Effects the mechanism of pain modulation
Electrical CircuitsElectrical Circuits
Path of current from power source through various components back to generating source • ______ ______ : electrons are flowing• ______ ______ : current flow ceases
Components of electrical circuits• ______ ______: capable of producing voltage• _________ _________: along which current travels• _________ _________: providing resistance to
electrical flow
Series CircuitSeries Circuit
Only ______ path for current to take Component resistors placed ______ to ______ Total resistance = sum of resistances Total voltage = sum of voltage decreases
Parallel CircuitParallel Circuit
Component resistors placed ___ to ___ and the ___ are connected
Current chooses path with least _________
Series Circuit vs. Parallel Series Circuit vs. Parallel CircuitCircuit
Component resistors in a series Component resistors in a series circuit have a circuit have a ____ resistance and resistance and _____ current flow current flow
Component resistors in a parallel Component resistors in a parallel circuit have a circuit have a _____ resistance and resistance and a a _____ current flow current flow
Current Flow Through Current Flow Through Biologic TissuesBiologic Tissues
Combination of both series and parallel circuits
Tissue highest in water and ion content are the best conductors • Bood, nerve, muscle, tendon, skin, fat, bone
Physiologic Responses to Physiologic Responses to Electrical CurrentElectrical Current
ThermalThermal• All electrical currents cause a All electrical currents cause a ____ in tissue in tissue
temperature temperature • Electrical currents used to stimulate nerve Electrical currents used to stimulate nerve
and muscle produce and muscle produce _______ thermal effects thermal effects ChemicalChemical
• At At ______ pole, negatively charged particles pole, negatively charged particles cause an cause an ______ reaction reaction – Protein coagulation and hardening of tissuesProtein coagulation and hardening of tissues
• At At ______ pole, positively charged particles pole, positively charged particles cause an cause an ______ reaction reaction– Liquefying protein and softening of tissuesLiquefying protein and softening of tissues
Safety In Using Electrical Safety In Using Electrical EquipmentEquipment
Ground Fault Interrupters Ground Fault Interrupters (GFI)(GFI)
Constantly compare amount of electricity flowing from wall outlet to whirlpool turbine with the amount returning
GFI will interrupt current flow in as little as 1/40 of a second
SummarySummary
TerminologyTerminology Ohm’s Law Ohm’s Law
• Relationship between voltage and Relationship between voltage and resistanceresistance
Different types of current are capable Different types of current are capable of producing specific physiologic of producing specific physiologic changeschanges• Thermal or chemicalThermal or chemical
Current modulationCurrent modulation