MCQ Practice Question
A conductor of cross-sectional area 2 mm² carries a uniform current of 4 A. The current density magnitude is?
Correct Answer: B. 2×10^6 A/m²
Explanation: Area=2×10^-6 m², so J=I/A=4/(2×10^-6)=2×10^6 A/m².
Reference: Standard electromagnetic theory: current density
