Answer:24.47
Explanation:
Given
[tex]L_1=30 m[/tex]
[tex]d_1=3 mm[/tex]
[tex]R_1=25 \Omega [/tex]
[tex]L_2=40 m[/tex]
[tex]d_2=3.5 mm[/tex]
we know Resistance [tex]R=\frac{\rho L}{A}[/tex]
Where R=resistance
[tex]\rho =resistivity[/tex]
L=Length
A=area of cross-section
[tex]A=\frac{\pi d^2}{4}[/tex]
Thus [tex]R\propto \frac{L}{d^2}[/tex]
therefore
[tex]R_1\propto \frac{L_1}{d_1^2}[/tex]--------1
[tex]R_2\propto \frac{L_2}{d_2^2}[/tex]--------2
divide 1 and 2 we get
[tex]\frac{R_1}{R_2}=\frac{L_1}{L_2}\times \frac{d_2^2}{d_1^2}[/tex]
[tex]\frac{R_1}{R_2}=\frac{30}{40}\times \frac{3.5^2}{3^2}[/tex]
[tex]R_2=25\times 0.734\times 1.33[/tex]
[tex]R_2=24.47 \Omega [/tex]
