A solid maintained at t1° C is kept in an evacuated chamber at temperature t2° C (t2 >>t1). The rate of heat absorbed by the body is proportional to
t24 − t14
(t24 + 273) − (t14 + 273)
t2 − t1
t22 − t12
C.
t2 − t1
As we know that, the rate of cooling is
where, bA = constant
where, T = temperature
and t = time
So, the rate of heat absorbed by cooled body is proportional to t2 − t1