NEET Exam Model Paper 12

A copper rod of length l1 and an iron rod of length l2 always maintained at the same common temperature T. If the difference (l2−l1) is 15 cm and is independent of the value of T, the l1 and l‌2 have the values (given the coefficient of linear expansion for copper and iron are 2.0×10−6C−1 and 1.0×10−6C−1 respectively) :-