Basic Principles of Electricity

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Basic Principles of Electricity
Jennifer L. Doherty-Restrepo, MS, LAT, ATC FIU
Entry-Level ATEP PET 4995 Therapeutic Modalities
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Electromagnetic Spectrum

Electrical Stimulating Currents
Longest Wavelength
Lowest Frequency
Commercial Radio and Television
Shortwave Diathermy
Microwave Diathermy
Infrared

LASER
Visible Light
Ultraviolet
Ionizing Radiation
Shortest Wavelength
Highest Frequency
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Electrons

• 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 ________

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Electrical Potential Difference

• Difference in ________ of electrons between two
  points
• Electrons will not move unless a ________
  difference exists

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Ampere

• 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)

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Volt

• Creates the electrical potential ________
• The __________ ________ which must be applied to
  create flow of electrons
• Commercial current (wall outlets) is either
  ________ or ________

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Conductors

• 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

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Insulators

• Materials that ______ the flow of electrons
• Contain ________ free electrons
• Insulator materials
• Air,
• Wood, and
• Glass

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Resistance Electrical Impedance

• ________ to flow of electrical current
• Measured in ________
• Unit of measure indicating resistance to current
  flow
• Ohms law current flow is ________ proportional
  to ________ and ________ proportional to ________
  
• Current flow Voltage
  Resistance

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Watt

• 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

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Electrotherapeutic Currents

• 3 types of currents capable of producing specific
  physiological effects
• ________
• ________
• ________
• Therapeutic effects of will be discussed in
  Chapter 8

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Direct Current (DC)

• Uniterrupted, uniderectional flow of electrons in
  the ________ direction
• Also called ________ currents
• Sometimes called ________ currents

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Alternating Current (AC)

• Continuous flow of electrons changes direction
• Always flows from ________ to ________ pole until
  polarity is reversed
• Also called ________ currents

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Pulsitile (Polyphasic) Currents

• ________ electrical current that contains __ or
  more grouped phases in a single pulse
• Also called ________ and ________ currents

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Electrical 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!

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Electrotherapeutic Currents

• 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

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Waveform or Pulse

• Pulse ________ ________
• Phases (duration)
• Interpulse interval
• Direction (polarity)
• Amplitude
• Rate of ________
• Rate of ________
• Accommodation

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Symmetrical Waveforms

• Sine
• Square
• Triangular
• Spiked
• ____ and _____ of each phase is identical

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Symmetrical Waveforms

• Twin peaked triangular waveform
• Found on most high volt generators

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Asymmetric Waveforms

• ________
• No longer used
• Effects were similar to DC pulsed wave
• ________
• Sawtooth
• Used to stimulate denervated muscle

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Current Modulation

• (A) Continuous
• (B) Interrupted
• (C) Burst
• Packets (envelopes)
• Pulse trains
• Beats
• (D) Ramped (Surge)

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Pulse Amplitude

• Amplitude current intensity voltage
• ______ ______ amount of current flowing per
  unit time
• Determined by interpulse interval or current
  duration
• Measured in ________ or ________

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Pulse 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 ______ ______

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Pulse Frequency

• Number of ______ or ______ per second
• Measured as pulses per second (PPS)
• Individual pulse rise and fall in amplitude
• As frequency ___________, amplitude ________ and
  ________ more rapidly

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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

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Electrical 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

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Series Circuit

• Only ______ path for current to take
• Component resistors placed ______ to ______
• Total resistance sum of resistances
• Total voltage sum of voltage decreases

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Parallel Circuit

• Component resistors placed ___ to ___ and the ___
  are connected
• Current chooses path with least _________

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Series Circuit vs. Parallel Circuit

• Component resistors in a series circuit have a
  ____ resistance and _____ current flow
• Component resistors in a parallel circuit have a
  _____ resistance and a _____ current flow

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Current Flow Through Biologic 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

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Physiologic Responses to Electrical Current

• Thermal
• All electrical currents cause a ____ in tissue
  temperature
• Electrical currents used to stimulate nerve and
  muscle produce _______ thermal effects
• Chemical
• At ______ pole, negatively charged particles
  cause an ______ reaction
• Protein coagulation and hardening of tissues
• At ______ pole, positively charged particles
  cause an ______ reaction
• Liquefying protein and softening of tissues

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Safety In Using Electrical Equipment
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Ground Fault Interrupters (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

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Summary

• Terminology
• Ohms Law
• Relationship between voltage and resistance
• Different types of current are capable of
  producing specific physiologic changes
• Thermal or chemical
• Current modulation