A) 10V/m
B) 5 V/m
C) 2 V/m
D) 0.5 V/m
Correct Answer: D
Solution :
Key Idea: Potential difference across any portion of the wire is proportional to the length of that portion. We know that voltage = current \[\times \] resistance \[\therefore \] \[i=\frac{E}{R}=\frac{2}{10}=0.2A\] From the principle of potentiometer when a constant current is passed through a wire of uniform cross-section the potential difference across any portion of the wire is directly proportional to the length of that portion i.e.,\[V=K\] So, potential difference per unit length of the wire, i.e., potential gradient \[k=\frac{V}{l}\] \[\therefore \] \[=\frac{iR}{l}=\frac{0.2\times 10}{4}=0.5\,\,\text{V/m}\]
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