Question

a 6 ohm resistance wire is doubled up by folding calculate the new resistance of the wire?

Answer 1

1.5 ohms
By folding it and connecting we get two 3 ohm resistors in parallel which equals to 1.5 ohms

Answer 2

Resistance=ρL/A

Here, Resistance=6ohm

Therefore,6=ρL/A

In second case,
Resistance,R'=ρL'/A'

As the wire is doubled so

L'=L/2, A'=2A

So new resistance,R'=ρL/4A

=(1/4)ρL/A

But ρL/A=6

So, R'=6/4=1.5Ω

Thus, The new Resistance is 1.5 ohm