Ohm’s law check: With a 10 Ω resistor across 20 V, what current flows? Assess the statement “4 A will flow.”

Introduction / Context:
Ohm’s law is the foundational relationship in basic circuits: V = I * R. Verifying numeric statements quickly is a frequent task during lab work and exams. Here we test a simple current computation.

Given Data / Assumptions:

• Resistor R = 10 Ω.
• Applied voltage V = 20 V (DC).
• Assume ideal source and resistor with no temperature effects.

Concept / Approach:
Use I = V / R. Substitution yields the true current. Compare the calculated current to the claimed 4 A.

Step-by-Step Solution:

Verification / Alternative check:
Cross-check with power: P = V * I = 20 * 2 = 40 W, and also P = I^2 * R = 2^2 * 10 = 40 W. Consistent results confirm 2 A.

Why Other Options Are Wrong:
Correct: Would imply 4 A, which violates Ohm’s law with the given values.

Common Pitfalls:
Arithmetic slips (dividing 20 by 5 instead of 10). Confusing series/parallel equivalents that change R. Ignoring that doubling current would require either doubling voltage or halving resistance.

Final Answer:
Incorrect