Lecture 17: Unsteady State Heat Conduction in a Semi-infinte Medium 

Prof. Suman Chakraborty

can you tell where this concept is used ???

@@nsai3757 This problem is of much much use where we can not measure temperatures on both sides of plate directly. For instance, consider a flat plate where some heating is taking place and we want to know the heat flux distribution. Then based on temperature measurements on one side of plate only and suitability of boundary condition (uniform temp or uniform heat flux or convective), we can actually determine heat flux distribution. See otherwise we need to have temperatures on both sides of plate so as to estimate the heat flux. With this method, temperature variation w.r.t. time on only one side of plate is sufficient to calculate the heat flux.

You are right buddy. when n=infinity i.e x is far away from wall, the temprature will become T=Ti. But for all practical purposes, if T-Ti

yes indeed