Question

The diameter of a metal ring is D and
coefficient of linear expansion is a, if the
temperature of the ring is increases by
1°C, the circumference of the ring will
increases by
ܘܠܐ: (A)
Da
2
(B)
27 Da
(C) Da
(D) D’a​

Answer 1

Increase in Diameter, ΔD =Dα

So, increase in circumference =πΔD =πDα

Also, we note that coefficient of area expansion =2α

So change in area = initial area × 2×α =

4

πD

2

× 2×α =

2

πD

2

α