Question #4dd5f

1 Answer
Nov 6, 2016

the ans. will be 1ohm.

Explanation:

we know R=s(l/a).where s=specific resistance of the element, l=length of the element,a=circular base area of the element.
now for the first case if resistance was R1 and for the second case resistance will be R2.
so R1=s(l1a1) and R2=s(l2a2)
now the diameter of the element is doubled ,so the radius of the circular base is also doubled.since,area=πr2,the area will be 4times.so,a2=4a1.
here the volume of the element will remain constant,so the product of the area & length remains the same i.e. a1l1=a2l2
again a2=4a1 hence l2=l14 .
since the element remains same s will be same for both the cases.

nowR2=s(l2a2)=sl144a1=s(l116a1)=R116=1616=1ohm.