Answer
Resistance would be 14.69 ohms
Work Step by Step
The resistance (in ohms) (R) of a circular conductor varies directly with the length L of the conductor and inversely with the square of the radius (A) of the
conductor.
=>$R = k\frac{L}{A^2}$
Given R = 10 ohms when L = 50 feet and $A = 6 \times 10^{-3} $ inch
=> $10 = k\frac{50}{(6 \times 10^{-3})^2}$
=> $k = 7.2 \times 10^{-6}$
To find R when L = 100 feet and $A = 7 \times 10^{-3} $ inch
=> $R = 7.2 \times 10^{-6} \times \frac{100}{(7 \times 10^{-3})^2} = 14.69\ ohms$
