Ohm's Law and Circuit Principles

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which type of current has a constant flow of electrons in one direction?

Alternating current (AC)

Direct current (DC) (correct)

Pulsatile current

Biphasic current

Biphasic unbalanced waveforms do not result in any polarity effect.

False

What is the main advantage of having polarity in an electrode?

It makes one electrode more active than another.

In iontophoresis, the polarity is primarily _____.

DC Signup and view all the answers

Match the following applications with their associated current type:

Iontophoresis = DC Acute edema treatment = HVPC Neuromuscular electrical stimulation (NMES) = Biphasic asymmetrical unbalanced waveform Pain relief = AC Signup and view all the answers

What is a disadvantage of using polarity in an electrode?

Increased charge accumulation Signup and view all the answers

Alternating current (AC) flows in only one direction.

False Signup and view all the answers

Describe what pulsatile current is.

Non-continuous flow of electrons delivered in pulses. Signup and view all the answers

According to Ohm's Law, what is the relationship between current (I), voltage (V), and resistance (R)?

I = V/R Signup and view all the answers

Current is inversely proportional to voltage.

False Signup and view all the answers

What is the unit of resistance in electrical circuits?

Ohm Signup and view all the answers

A device producing a constant ______ produces a current that does not vary regardless of changes in resistance.

current Signup and view all the answers

Match the following terms with their descriptions:

Monophasic = Pulses flow in one direction Biphasic = Pulses alternate above and below the 0 line Constant Voltage = Voltage remains the same, but current varies Constant Current = Current remains the same, regardless of resistance changes Signup and view all the answers

What is a major advantage of constant current devices?

Consistent physiological response Signup and view all the answers

Biphasic waveforms produce a polarity effect only if they are balanced.

False Signup and view all the answers

What happens to the quality of response in constant voltage devices as resistance changes?

Changes or may become less effective Signup and view all the answers

Electromotive force is another term for ______.

voltage Signup and view all the answers

Study Notes

Ohm's Law

Ohm's Law describes the relationship between current, voltage, and resistance.
I = V/R (Current equals Voltage divided by Resistance)
Current (I) is directly proportional to voltage (V)
Current (I) is inversely proportional to resistance (R)
Current (I): the rate of flow of electrically charged particles (electrons in metals, ions in biological tissues). Measured in Amps, milliamps, or microamps.
Voltage (V): the driving force that causes charged particles to move. Measured in volts or millivolts.
Resistance (R): the opposition to current flow. Measured in Ohms.

Constant Current vs. Constant Voltage

Constant Current: Devices maintain a consistent current output, regardless of changes in resistance.
- Advantage: Provides a consistent physiological response, similar to cruise control.
- Disadvantage: If electrode contact is lost or compromised, current concentrates in the areas with contact.
Constant Voltage: Devices maintain a constant voltage output. Current changes as resistance changes.
- Disadvantage: The quality of the response varies with changes in resistance, potentially making the treatment less effective or comfortable.

Waveforms

Description: Waveforms are graphic representations of electrical current characteristics, including amplitude, duration, and frequency.
Interpretation: Waveforms visually illustrate the specific characteristics of the electrical current.
Monophasic: Current flows in one direction (either anode to cathode or cathode to anode) the entire time. Produces a polarity effect.
Biphasic: Current changes direction. Produces a polarity effect only if unbalanced.
Polarity: Electron flow in one direction (monophasic, and sometimes with unbalanced biphasic waveforms). One electrode is positive, the other negative.
- Therapeutic Applications (greatest to least effect): Iontophoresis (DC), acute edema (HVPC), NMES (pulsed current: biphasic asymmetrical unbalanced waveform).
- Advantage of Polarity: Can make one electrode more active than another.
- Disadvantage of Polarity: Potential for discomfort or burns.
Direct Current (DC): Constant flow of electrons in one direction for more than a second. Polarity is based on the intended treatment outcome.
Alternating Current (AC): Continuous flow with current constantly reversing from positive to negative. Sinusoidal pattern.
Pulsatile: Non-continuous flow with pulses in one direction (monophasic) or both directions (biphasic). Biphasic can be balanced (no polarity) or unbalanced (mild polarity effect).

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers the fundamentals of Ohm's Law, including the relationships between current, voltage, and resistance. It explores constant current versus constant voltage principles, providing an understanding of how these concepts apply in electrical circuits. Perfect for students looking to test their knowledge in electrical engineering concepts.