Given, coefficient of linear expansion α=1×10−5∘C−1 Change in temperature, ∆T=25−(−15) =40∘C Since, change in length, ‌∆L=Lα∆T ⇒‌
∆L
L
=α∆T ⇒‌‌‌
∆L
L
=1×10−5×40 ⇒‌
∆L
L
=4×10−4 ∵ Percentage change in measurement of length, ‌