Probability of finding a particle in the position range a to b in the energy eigenstate in position space,$\psi_n $ is given by integral over the absolute squared wave function.For momentum range a to b,we transform the position space wave function to momentum space and integrate over the interval.


What to do for other physical observables?
e.g.--If I want to find what is the probability of finding the particle in the energy range E1 to E2 or What is the probability that the particle has angular momentum in the range L1 to L2...How to approach the problem?