Question

wire of length L area a and resistance R is doubled by stretching find the new resistance of the wire after stretching what will be the resistivity after stretching​

Answer 1

Answer:

The resistance will be four time of the initial

Explanation:

According to the problem the length of the wire is L

and area of the wire is a

and the resistance is R

According to the formula of resistance,

R=ρL/a [ where ρ is resistivity]

Now after stretching the  new resistance be  

R'=ρL/a'

Now we know from the conservation theory that volume of the wire remains same.

Therefore,

a'L' =aL

Now L'= 2L then a will be a/2

therefore the new resistance,

R'=ρ×2L/a/2

   =4ρL/a

     =4R