More Questions from Resistance and Power

With Ohm’s law in mind, if the applied voltage increases while the resistance remains unchanged, what happens to the circuit current (qualitatively)?

Electronics Resistance and Power Difficulty: Easy
Choose an option
  • A
    current remains the same
  • B
    power decreases
  • C
    current increases
  • D
    resistance decreases
  • E
    current 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

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