Let A and B be vector operators. This means that they have certain
nontrivial commutation relations with the angular momentum operators.
Use those relations to prove that A·B commutes with Jx, Jy, and
Jz.
In the set up photoelectric effect of light radiation..it is said that the electrons after being ejected form the photosensitive plate get acclerated towards the (+ve)high potential plate..due force acting on them(in presence of electric field setup by connecting battery)...then my question is ....how a constant value of current flows through the circuit if these electrons are randomly accelerated??????.....
(consider that we have maintained a constant potential)
I am thinking for some hours about the commutation of the field-Operator/(annihilation-Operator): $$\Psi$$ and the vector-potential: $$\vec{A(\vec{r})}$$.
I have noticed in my lecture notes that $$\vec{A(\vec{r})}\Psi = \Psi\vec{A(\vec{r})}$$.