Physics · Electric current: drift velocity, mobility and their relation with electric current
Given a current carrying wire of non- uniform cross-section. Which one of the fo
Given a current carrying wire of non- uniform cross-section. Which one of the following is constant through out the length of wire?
- A. Current only
- B. Current and drift speedd
- C. Drift speed only
- D. Current, electric field and drift speed
Step-by-step solution
In a steady current, the current (I) is constant throughout the wire due to conservation of charge, even if the cross-sectional area varies. Drift speed depends on area (v_d = I/(n e A)), so it changes with cross-section. Electric field also depends on area (E = I/(σ A)), so it is not constant. Thus only current remains constant.
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