Electron with energy 2 eV is incident on a barrier 6 eV high and 5 nm wide. (1) Find its transmission probability. (I) How is it modified if the width of the barrier is halved? (ii) Calculate the ratio of population of the two levels (N/NL) involved in lasing for a CO2 laser at a temperature of 3000 K. The difference in energy levels between the levels involved in laser transition is 0.121 eV.