A piece of copper is to be shaped into a conducting wire of maximum resistance. The suitable length and diameter are ………… and ………… respectively.

Options

A. L and d
B. 2L and d
C. L/2 and 2d
D. 2L and d/2

Answer

D

Explanation

We know that,
`R=(rho1)/(A)=(rho1)/(pi r^(2))=(rho1)/(pi r^(2))`
If the length of wire is increases, then the radius of wire is decreases.
To get the maximum resistance the suitable and diameter are 2L and d/2.