Question

what happens to resistance when length of conductor is doubled without affecting the thickness of conductor ​

Answer 1

Since we know that Resistance ∝ length / Cross section area

So, R = þ × l / A __(i)

When length of resistor is doubled then,

R' = þ × 2l / A __(ii)

By dividing both equations

R' / R = ( þ × 2l / A ) × ( A × 1 / þl )

R' / R = 2 or R' = 2 × R

Hence the new resistance will be double of initial one.

Conclusion :

In directly proportional values, when length will be doubled then Resistance will also double but when area will double the resistance will be reduced to half.

Answer 2

if the length will be doubled , we will getR=2R