Question

Two cylindrical resistors are made from copper. The first one is of length L and of radius r . The 2nd resistor is of length 6L and of radius 2r. The ratio of these two resistances R1/R2 is:

Answer 1

Answer:

$R1/R2=\frac{2}{3}$

Explanation:

From the question we are told that:

1st's Length $l=L$

1st's radius $r=r$

2nd's Length $l=6L$

2nd's radius $r=2r$

Generally the equation for Resistance R is mathematically given by

 $R=\frac{\rho L}{\pi r^2}$

Therefore

 $R_1=\frac{\rho L}{\pi r^2}$

And

 $R_2=\frac{\rho 6L}{\pi (2r)^2}$

Therefore

 $R1/R2=\frac{\frac{\rho L}{\pi r^2}}{\frac{\rho 6L}{\pi (2r)^2}}$

 $R1/R2=\frac{2}{3}$