Question

How does the resistance of a wire change when: 

its material is changed to one whose resistivity is three times?

Answer 1

Resistance,  

`R=l/A`

 where l = length of  wire
            A= area of cross-section of the wire 

 When the material is changed to one whose resistivity is three times:

New resistivity, `p'=33rho` 

The new resistance,  

`R'=(rho^eta)/A` 

`R=(3rho)/A=3R`

 

Thus, the resistance will become three times the original resistance.