Question 1

The coefficient of linear expansion of a solid is defined as?

Accepted Answer

Fractional change in length per unit rise in temperature. Linear expansion coefficient tells how much length changes per degree. It equals (change in length)/(original length × temperature change). It is usually treated constant for a small temperature range.

Question 2

For an isotropic solid, the coefficient of superficial expansion (β) is approximately?

Accepted Answer

β = 2α. In isotropic solids, area expands in two perpendicular directions. So the superficial expansion coefficient is about twice the linear coefficient. This relation is valid for small temperature changes.

Question 3

The SI unit of the coefficient of linear expansion is?

Accepted Answer

K^-1. Coefficient of linear expansion represents change per unit temperature. So its unit must be the inverse of temperature. In SI, it is per kelvin (K^-1).

Question 4

The correct formula for linear expansion is?

Accepted Answer

ΔL = αLΔT. Linear expansion is directly proportional to original length and temperature rise. The proportionality constant is α. Therefore ΔL = αLΔT.

Question 5

For an isotropic solid, the coefficient of cubical expansion (γ) is approximately?

Accepted Answer

γ = 3α. Volume expansion happens along three independent dimensions. So cubical expansion coefficient is about three times the linear coefficient. This is a good approximation for small temperature changes.

Expansion — Set 1