Question

There are two wires of same material and same length while the diameter of second wire is two times the diameter of first wire, then the ratio of extension the diameter of first wire, then the ratio of extension produced in the wire by applying same load will be _____________

(a) 1:1

(b) 2:1

(c) 1:2

(d) 4:1

I got this question in examination.

Question is from Elastic Limit topic in division Thermal Properties of Matter of Engineering Physics I

Answer 1

The correct option is (d) 4:1

For explanation: Extension,

∆l=F/A  l/Y=F/(πr^2)  l/Y

For the two wires F, l and Y are same, so

(∆l1)/(∆l2)=((r2)^2)/((r1)^2)=(2/1)^2 4:1.