I'm trying to "sure"up my Quantum Mechanics and found an sheet of mostly conceptual review questions. A sort of "Quantum minima". I'd like to check my answers to a couple of these. Firstly: In terms of state vector the wavefunction is the expansion coefficient (probability amplitude) of a state i.e [tex] \psi = \langle x \left | \psi \right\rangle [/tex] What happens if you put an operator (e.g. p) between the bra and ket as if you were calculating an expectation value? i.e. [tex] \left\langle x \left | p \right | \psi \right \rangle [/tex] My guess is that the action of the operator on the state vector [itex]\left|\psi\right\rangle[/itex] will collapse the vector to a single basis vector of p [itex]\left| p \right\rangle [/itex] the expression above would reduce to an element of a basis transformation matrix [itex]\left\langle x | p \right\rangle [/itex] Is that correct...at least in part?