Thermal expansion is the increase in the dimensions of a substance when its temperature is increased.
Most materials expand on heating and contract on cooling.
On heating, the particles of a substance gain energy, vibrate more vigorously and move farther apart, resulting in expansion.
Increase in length of a solid due to rise in temperature.
ΔL = α L ΔT
where,
α = coefficient of linear expansion
L = original length
ΔT = change in temperature
Increase in area of a solid due to rise in temperature.
Increase in volume of a substance due to rise in temperature.
ΔV = γ V ΔT
where,
γ = coefficient of cubical expansion
It is defined as the increase in length per unit original length per degree rise in temperature.
Q1. Thermal expansion occurs due to: A) Decrease in temperature B) Increase in temperature C) Increase in pressure D) Decrease in pressure Answer: B Q2. Linear expansion refers to change in: A) Area B) Volume C) Length D) Mass Answer: C Q3. Formula for linear expansion is: A) ΔL = L / ΔT B) ΔL = α L ΔT C) ΔL = γ V ΔT D) ΔL = L α / ΔT Answer: B Q4. Cubical expansion refers to change in: A) Length B) Area C) Volume D) Shape Answer: C Q5. Coefficient of linear expansion depends on: A) Shape of body B) Material of body C) Length of body D) Temperature only Answer: B Q6. On heating, most solids: A) Contract B) Expand C) Melt immediately D) Break Answer: B Q7. Which device works on thermal expansion? A) Ammeter B) Voltmeter C) Bimetallic strip D) Barometer Answer: C Q8. Gaps are provided in railway tracks to: A) Improve speed B) Reduce friction C) Allow expansion D) Increase strength Answer: C
Increase in dimensions of a body due to rise in temperature.
ΔL = α L ΔT
MCQs are asked on types of expansion, formulas and daily-life applications.
