Week 5 Review Flashcards
Which of the following is the correct description of “charge”?
Gain or loss of electrons by an atom
According to Ohm’s law, when using a device that has a constant voltage, what will happen to the current amplitude when the skin resistance increases?
the current decreases
Which type of current will most likely cause changes in the tissues underlying the electrodes as a result of electrode polarity?
direct current
Which of the following is true regarding the strength-duration curve for electrical stimulation?
It depicts the response of a nerve to stimulation for a given pulse amplitude and duration.
Which electrochemical effects match the given electrode polarity?
the alkaline reaction under the cathode results in softening of the underlying tissues.
According to Ohm’s law, an 80 volt (V) circuit passing through 4 ohms of tissue impedance (resistance) will have how many amps (A) of current?
Ohm’s law:
I = V/R or
I (current in amperes) = Voltage/Resistance
20 A
Which of the following statements is true about charge?
Charge is neither created nor destroyed.
The force of attraction or repulsion created by an electric field that represents potential energy is known as
voltage
Why are human body tissues such as muscles, nerves, and blood good conductors of electric current?
These tissues have a high water content and presence of ions.
Which of the following is the correct description of “direct current”?
Unidirectional flow of electrons for at least 1 second
If the phase durations of a biphasic pulse are 150 μsec each and the interphase (or intrapulse) interval is 50 μsec, what is the total pulse duration?
350 μsec
What can be done clinically to decrease impedance between the electrode and the skin?
Use electrodes with gel or adhesive conductive agents.
The unidirectional or bidirectional flow of ions or electrodes that periodically ceases for a small period of time before the next electrical event is known as
Pulsed or pulsatile current
Why is the electrochemical effect negligible when using monophasic pulsed currents such as high-volt pulsed current (HVPC)?
Short pulse durations and long interpulse intervals prevent accumulation of charges.
The greatest amount of electrothermal heating occurs with which of the following currents?
direct current
Why does electric current depolarize nerves more easily than it does skeletal muscles?
The resting membrane potential of nerves is less negative than that of muscles.
When stimulating a mixed peripheral nerve, which type of nerve fibers will be recruited first?
type A alpha
Which of the following describes the typical characteristics of what is commonly known as “Russian current”?
2,500 Hz alternating current, burst modulated at 50 bursts per second using 10-msec bursts
Which of the following best describes interferential current (IFC)?
Superimposition of two symmetrical, asynchronous, sinusoidal alternating currents
Low-intensity direct current (LIDC) is most commonly used clinically for which of the following?
Promotion of wound healing by augmenting the current of injury
Which of the following will occur in a constant current (CC) device if the resistance to current flow in biological tissues increases?
voltage will increase
Which of the following correctly describes “pulse duration”?
total time elapsed from beginning to end of all phases, including interphase interval
How often can a typical disposable electrode be reused before it should be discarded?
18 to 20 times on average
Which of the following statements is correct regarding electrode placement?
The best electrode placement for a given treatment may require some trial and error.
