Current Electricity and Electrical InstrumentHard
Question
An electric current flows along an insulated strip PQ of a metallic conductor. The current density in the strip varies as shown in the graph. Which one of the following statements could explain this variation?
Options
A.The strip is narrower at P than at Q
B.The strip is narrower at Q than at P
C.The potential gradient along the strop is uniform
D.The potential gradient along the strop is uniform
Solution
The current density at P is higher than at Q. For the same current flowing through the metallic conductor PQ, the cross - sectional area at P is narrower than at Q. The resistance per unit length r is given by r = 
Where ρ is the resistivity and A is the cross-sectional area of the conductor PQ. Thus, r is inversely proportional to the cross - sectional area A of the conductor
Where ρ is the resistivity and A is the cross-sectional area of the conductor PQ. Thus, r is inversely proportional to the cross - sectional area A of the conductor
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