Rydberg atoms are nearly classical atoms in which electron is excitedto states corresponding to n = 10 , 2 0 or even 100. There are many difficulties in studying them. 1. The radius of their orbit will be very large. So at ordinary densities, their collisions will allow electrons to jump from one orbit to another without emitting radiation. 2. The energy levels at such value of n will be every close. So experiment on rydberg atoms should be done at very low temperatures and very low pressures. Consider a very dilute gas of hydrogen atoms that are excited to n = 10. Assume for this situation that the average centre to centre distance should be equal to diameter of rydberg atom. [Take wein constant = 2.88xx10^(-3) mK] If this energy were to come from a photon corresponding to maximum spectral emissive power of a blackbody, what would be the temperature of that black body.