Electrotherapeutic Basics Flashcards
What 3 things must be present to have a current
- A source of electrons
- A conductor of the electrons
- A driving force of electrons
What are atoms that possess charge known as
Ions
Where do ions move from and to
From areas of high concentrations to areas of low concentrations
What is the net movement of charged particles along a conductor
Current
What is the amount of potential (electrical) difference between two points ([ions] or electrons) in an electrical field
Electromotive force (EMF)
What does the electromotive force do
Drives the charged particles that are measured in volts
What size electromotive does the commercial current flowing from a wall outlet produce (2)
- 110-115 V
2. 220-240 V
True or False:
Electrotherapeutic modalities modify voltage for specific therapeutic purposes
True
True or False:
In the human system the electric stimulator generates a voltage to overcome resistance allowing a current to flow along the path of least resistance
True
What makes an electrotherapeutic modality a low voltage generator
Produces a voltage less than 150 V
What makes an electrotherapeutic modality a high voltage generator
Produces a voltage greater than 150 V
What is a coulomb (C)
The measure of electric charge equal to 6.25*10^18 electrons
What is an ampere (A)
The measure of current flow equal to 1 C per second
What is an Ohm (omega)
Measure of resistance to current flow
What is voltage (V)
Measure of the potential difference or EMF required to move 1 A of current across 1 Ohm of resistance
What is resistance (Ohms)
The ability of a medium to resist the flow of electrons through direct current
What is inductance
Opposition to electron flow created by electromagnetic eddy currents generated when current is passed through a wire
What is capacitance
Ability of a material to store an electrical charge
What is impedance
Resistance + inductance + capacitance
What are conductors
Materials that offer little resistance and allow current to flow easily
What are insulators
Materials that offer high resistance to current flow
What are semiconductors
Materials that offer neither high nor low resistance to current flow
What is the pump of water flow equal to in electron flow
Volts
What is the gallons of water/min equal to in electron flow
Ampere
What is the length and diameter of the pipe equal to in electron flow
Resistance
Energy created by water flowing is dependent on what (2)
- Pressure in the pipe
2. # of gallons flowing per unit of time
What is electrical power measured in
Watts
What do watts equal
Volts*amps
What does power equal
EMFcurrent (VI)
What is 1 watt equal to
The power needed to move one ampere of current with a force of one volt
What is Ohm’s Law
The amount of electromotive force in a circuit is equal to the current intensity multipled by the resistance
What is the equation of Ohm’s Law
V=I*R
What does increasing the resistance do the the voltage to move current
Increases the voltage
What is a circuit that is in series
When the same current flows through each resister
What does total resistance equal in a circuit in series
Rt=R1+R2+…
What is a circuit that is in parallel
When current flowing through a circuit has multiple pathways to follow through or around each resister
What does total resistance equal in a circuit in parallel
1/Rt=1/R1+1/R2+…
What are the 3 basic electrotherapeutic currents
- Direct (DC)
- Alternating (AC)
- Pulsatile or pulsed
What are the 3 types of direct/galvanic/monophasic current
- Continuous
- Reversed DC current
- Interrupted DC current
What is continuous direct current
Unidirectional flow of electrical charges for at least one second
What is reversed DC current
Unidirectional flow of electrical charges for at least one second that then changes polarity
What is interrupted DC current
Unidirectional flow of electrical charges for at least on second that then stops for at least on second then resumes
What is direct current generally used for (3)
- Iontophoresis
- Stimulating denervated muscle directly
- Stimulate wound healing
What is alternating/faradic/biphasic current
A continuous bidirectional flow of charged particles where each cycle duration occurs in less than one second with equal ion flow in each direction
What does equal ion flow in each direction cause during AC current
No net charge to be formed
What does the wavelength equal in AC current
One cycle
True or False:
In AC current wavelength and frequency are inversely related
True
What is AC current generally used for (4)
- Muscle strengthening
- Muscle re-education
- Pain modulation
- Functional training
What is pulsatile/pulsed current
Unidirectional flow of electrical current that lasts less than one second and stops for a finite period before the next pulse
How long is the finite amount of time that pulsed current stops for
Usually 5-999 milliseconds
What is a dumbed down way to explain pulsed current
Electric current delivered discontinuously separated by a finite period of time
What are the 2 types of pulsed currents
- Monophasic pulsed current
2. Biphasic pulsed current
What are the 2 types of biphasic pulsed current
- Symmetric
2. Asymmetric
What are the 2 types of asymmetric biphasic current
- Balanced
2. Unbalanced
What makes the asymmetric biphasic current balanced and unbalanced
Balanced: The area under the wave is the same (so same charge) for both waves but different length of time
Unbalanced: The area under the wave is different (so different charge) but the length of time is the same
Does balanced or unbalanced asymmetric biphasic current result in the build up of current on one side
Unbalanced
What is the waveform
The shape of the current intensity vs. time graph
What are the possible number of phases (4)
- Monophasic
- Biphasic
- Triphasic
- Polyphasic
what are the possible symmetries of phases (2)
- Symmetry
2. Asymmetry
What are the possible balances of charge (2)
- Balanced
2. Unbalanced
What are the possible waveforms or phase shapes (5)
- Rectangular
- Square
- Triangular
- Saw tooth
- Sinusoidal