Ohm's law describes the mathematical relationship between which set of quantities used to calculate basic circuit behavior?
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Aohms, kilohms, and megohms
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Bresistor size and resistor value
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Cresistance, voltage, and current
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Dnone of the above
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Epower factor, frequency, and phase
Answer
Correct Answer: resistance, voltage, and current
Explanation
Introduction:This question reinforces the definition of Ohm's law from a descriptive angle. Correctly identifying the variables tied by the law is essential for solving everyday circuit problems, from selecting series resistors for LEDs to estimating supply current.
Given Data / Assumptions:
- Ohmic components with linear V–I behavior.
- Steady-state conditions for DC, or instantaneous relationships for resistive AC.
Concept / Approach:Ohm's law: V = I * R links voltage (V), current (I), and resistance (R). Units (ohms, kilohms, megohms) are scales of resistance, not separate physical quantities governed by the law.
Step-by-Step Solution:Recognize variables: resistance (R), voltage (V), current (I).Recall the identity: V = I * R.Derive forms: I = V / R and R = V / I.Apply to examples: choose R to set I for a given V in a simple series circuit.
Verification / Alternative check:Plotting measured current against applied voltage for a fixed resistor yields a straight line with slope 1/R, confirming the relationship between the three quantities.
Why Other Options Are Wrong:
- ohms, kilohms, and megohms: Merely unit prefixes for resistance.
- resistor size and resistor value: Physical size does not define the Ohm's law relationship.
- none of the above / power factor set: Do not describe Ohm's law.
Common Pitfalls:
- Assuming large physical resistors always have large resistance; power rating and resistance are different specifications.
- Confusing derived power equations with the primary Ohm's law identity.
Final Answer:resistance, voltage, and current