Question

A wire of resistance $4\Omega$ is stretched to double its original length. The resistance of the stretched wire would be

• A. $2\Omega$
• B. $4\Omega$
• C. $8\Omega$
• D. $16\Omega$

Answer 1

The correct option is D $16\Omega$

the volume of the wire remains the same. $Al=constant$. So when length is doubled, area becomes half.

Using the formula $R=\rho \frac{l}{A}$ we get the new resistance as 4 times the initial value. Thus D is correct.