Ans 14
Q.14. A piece of wire is redrawn by pulling it until its length is doubled. Compare the new resistance with the original value?

Dear student,
The Resistance R=ρl/A where
l= length of the wire
A= Area of crossection of wire
Since, the length of the wire is doubled so, l'=2l
Since, for a change in conductor the mass And density remains intact and area changes in the equal inverse proportion
So, area A'=A/2
R'=ρl'/A'
R'=ρ2l/A/2
R'=4ρl/A
R'=4R
So, the new resistance will be equal to the four times of the original resistance.
Regards