(a) Estimate the particle density necessary for bose-Einstein condensation of a
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Question
(a) Estimate the particle density necessary for bose-Einstein condensation of a hydrogen gas to occur at 100 nK. (b) what is the ratio of the thermal wavelength to the atom spacing?
1-A mechanically isolated system had a net gain of particles thought its entropy remained the same what cam say about its energy
2-Is possiple to deduce Avogadro number from some measurements of Brownian motion?if so,how? assume the ideal gas constant(R) is independently known
3- say a biologist is unhappy that entropy always seems to increase, and decides to plant some flowers to absorb the heat from sun light will decrease the entropy of covered ground ? if so,have we beaten the second law?
Explanation / Answer
1)Entropy of the universe always increases. If entropy of the system remains the same, that means entropy of the surroundings increases. so, energy flows out of the system. Energy of the system decreases. 3)No. If ground gets cooled, that means the energy is flowing into the air or some other object. The increase in entropy of that object is greater than decrease in entropy of ground. So, net entropy of system and surroundings increase.
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