# Problem 3.26 in Griffiths' Introduction to Quantum Mechanics

This is problem 3.26 in Griffiths' Introduction to Quantum Mechanics (second editition):

An anti-hermitian (or skew-hermitian) operator is equal to minus its hemitian conjugate:

(a) Show that the expectation value of an anti-hermitian operator is imaginary.

(b) Show that the commutator of two hermitian operators is anti-hermitian. How about the commutator of two anti-hermitian operators?

https://brainmass.com/physics/quantum-physics/problem-3-26-in-griffiths-introduction-to-quantum-mechanics-39436

#### Solution Preview

For a hermitian operator, A* = A

and for an anti hermitian one, A* = -A

I used "* " for DAGGER

first I will show u that the expectation value of hermitian operator is real

<psi|A|psi>* = <psi|A|psi> = <A>, the expectation value of ...

#### Solution Summary

The answer with good explanations.

$2.19