Answer:
Current would decrease 9 times.
Explanation:
Assume all others (potential difference U, resistivity ρ, and length L) are the same, only change in the diameter, we would have the following ratio
[tex]\frac{I_1}{I_2} = \frac{U/R_1}{U/R_2} = \frac{U}{U}\frac{R_2}{R_1} = \frac{\rho L/A_2}{\rho L / A_1} = \frac{\rho L}{\rho L}\frac{A_1}{A_2} = \frac{\pi d_1^2/4}{\pi d_2^2/4} = \frac{4\pi}{4\pi}\left(\frac{d_1}{d_2}\right)^2 = 3^2 = 9[/tex]
[tex]I_2 = I_1/9[/tex]
So the current would decrease 9 times.
