There is one rod of metal whose electrical resistance is R. What will be the new resistance if the rod is stretched to
(a) double its initial length?
(b) increase its length by double of its initial length ?
Assume that density of material remains constant.

Explanation

To solve the problem, we need to understand how the resistance of a rod changes when its dimensions are altered while keeping the volume constant. The resistance \( R \) of a rod is given by the formula:

\[ R = \frac{\rho L}{A} \]

where:
- \( \rho \) is the resistivity of the material,
...