Ohm's Law: Current is directly proportional to voltage for fixed resistance

Steps:

• Recall Ohm's law: V = I × R, where R is constant.
• Rearrange to I = V / R, showing direct proportionality.
• Plot I versus V: straight line through origin with slope 1/R.
• Identify graph matching linear increase from (0,0).

Why A is correct:

• A depicts a straight line through origin, matching I ∝ V from Ohm's law.

Why the others are wrong:

• B shows nonlinear curve, implying variable resistance.
• C shows constant current, ignoring voltage change.
• D shows decreasing current, contradicting direct proportionality.

Final answer: A