State three factors on which depend the linear expansion of a metal rod on heating.
Factors on which increase in the length of a rod depends when heated are:
(1) Length of rod L. Increase in length is directly proportional to original length.
(2) Temperature of the rod. It is directly proportional to the increase in temperature.
(3) Nature of material of rod.
If L1 is the original length of the rod at t1 °C and on heating to t2 °C its length becomes L2.
∴ Increase in length of rod = ( L2 – L1)
and an increase in temperature ( t2 – t1)
∴ [L2 – L1] ∝ L1 (t2 – t1)
But the increase in the length of the rod does not depend on whether the rod is solid or hollow.