WAEC Physics 2013 Paper

Concept:Thermal expansion is the change in size of a substance due to a change in temperature.Explanation:The amount by which a substance expands or contracts is given by $\Delta L = \alpha L_0 \Delta T$.Here, $\Delta T$ represents the temperature change, so statement i is correct.The coefficient $\alpha$ is a property that depends on the nature of the substance, so statement ii is correct.$L_0$ is the original size of the substance, so statement iii is correct.Therefore, all three factors together determine the magnitude of expansion or contraction.Answer:D. i, ii and iii