When a potential difference of 10 V is placed across a certain solid cylindrical resistor,the current through it is 2 A.If the diameter of this resistor is now tripled,the current will be
A) 2/9 A.
B) 2/3 A.
C) 2 A.
D) 3 A.
E) 18 A.

Question

Quizplus · Accepted Answer

The resistance of a cylindrical resistor is inversely proportional to the cross-sectional area, which depends on the square of the diameter. Tripling the diameter increases the area by a factor of 9, reducing the resistance by a factor of 9. Since current is inversely proportional to resistance (I = V/R), the current increases by a factor of 9, resulting in 18 A.

When a Potential Difference of 10 V Is Placed Across