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Class 12 › Physics › Current Electricity
CBSE2020Class Class 12 · Physics1 Marks · Mcq✅ Verified
A steady current flows in a metallic conductor of non-uniform cross-section. Which of the following quantities is constant along the conductor?
A. current
B. drift speed
C. current density
D. none of these
✅ Answer & Solution
✅ Correct Answer: A
Current $I$ is constant throughout by conservation of charge (KCL).
- Current density $J = I/A$ varies because $A$ is non-uniform.
- Drift velocity $v_d = I/(nAe)$ varies with $A$.
- Electric field $E$ also varies.
Only current $I$ remains constant.
