A blacksmith heated a metal whose cubic expansivity is 6.3 x 10-6K-1. The areal expansivity is
-
A.
2.0 x 10-6K-1 -
B.
2.1 x 10-6K-1 -
C.
4.2 x 10-6K-1 -
D.
6.3 x 10-6K-1
Correct Answer: Option C
Explanation
If the lineal expansivity = ∝
=> area expansivity β= 2∝.
And cubic expansivity δ = 3∝.
=> 6.3 x 10-6 = 3∝
∴ ∝ =
| ∴ ∝ = | 6.3 x 10-6 | = 2.1x 10-6 |
| __3 |
∴ Area = 2∝ = 2 x 2.1×10-6
= 4.2 x 10-6K-1