A cylindrical rod having temperature T1 and T2 at its end.

A cylindrical rod having temperature T₁ and T₂ at its end. The rate of flow of heat is Q₁ cal/sec. If all the linear dimensions are doubled keeping temperature constant, then the rate of flow of heat Q₂ will be

Q =	KA(θ₁ - θ₂)t
	l

Rate of heat flow

H =	Q	=	KA(θ₁ - θ₂)	i.e., H ∝	A
	t		l		l

Dimensions of area A = [L²], dimensions of distance l = [L]

∴ H ∝ L ⇒	H₂	=	L₂	= 2 ⇒ H₂ = 2H₁
	H₁		L₁