Question

One wire has a cross-sectional area of 1,250 circular mils and a resistance of 7 ohms. a second piece of wire, identical except for cross-sectional area, has a resistance of 10 ohms. determine what the cross-sectional area of this second wire is. (cross-sectional area and resistance are inversely proportional.)

Answer 1

As we know that resistance of the wire depends upon the area, length and its material

its formula is given by

`R = \rho (L)/(A)`

so from above we can say that

Since all other parameters are same except area of the wire so we can say

`(R_1)/(R_2) = (A_2)/(A_1)`

`(7)/(10) = (A_2)/(1250)`

`A_2 = 875 circular mils`

So area of 2nd wire is less than the first wire and its magnitude is 875 circular mils.