ex_5668_sol_Y11: Wrong solution of second part, and consistency with item(1) not demonstrated. ex_5668_sol_Y12: "with the addition of angular momentum"??? ex_5668_sol_Y13: Misleading introduction of the velocity in the Hamiltonian. See forum. ex_5668 V להשאיר בשיעורי בית[search the forum for more comments on this exercise]