With Ohm’s law in mind, if the applied voltage increases while the resistance remains unchanged, what happens to the circuit current (qualitatively)?
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Acurrent remains the same
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Bpower decreases
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Ccurrent increases
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Dresistance decreases
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Ecurrent decreases
Answer
Correct Answer: current increases
Explanation
Introduction / Context:Predicting how current responds to changes in voltage or resistance is foundational for circuit design. This understanding helps in component derating, fuse sizing, and thermal management.
Given Data / Assumptions:
- Resistance is constant (linear resistor).
- Applied voltage increases.
- Ambient and temperature effects ignored.
Concept / Approach:Ohm's law states I = V / R. With R fixed, any increase in V proportionally increases I. Power also changes: P = V * I = V^2 / R, implying a quadratic rise in power with voltage increases.
Step-by-Step Solution:Start from I = V / R.Increase V; R constant implies I must scale up linearly with V.Implication: P rises as V^2 / R, stressing components and possibly requiring higher wattage ratings.
Verification / Alternative check:Example: If V rises from 5 V to 10 V across 1 kΩ, current doubles from 5 mA to 10 mA, confirming the direct proportionality.
Why Other Options Are Wrong:“Current remains the same” contradicts I = V / R.
“Power decreases” is false; power increases with V at constant R.
“Resistance decreases” changes a different variable; R is constant by premise.
“Current decreases” is opposite of the correct relationship.
Common Pitfalls:Neglecting power dissipation when increasing voltage can cause resistor overheating or device failure.
Final Answer:current increases