Answer
$L = 3.65\times 10^{-34}~J~s$
Work Step by Step
We can find the magnitude of the orbital angular momentum in a state with $l = 3$:
$L = \sqrt{l(l+1)}~~\hbar$
$L = \sqrt{(3)(3+1)}~~\hbar$
$L = \sqrt{12}~~\hbar$
$L = \frac{\sqrt{12}~h}{2\pi}$
$L = \frac{(\sqrt{12})~(6.626\times 10^{-34}~J~s)}{2\pi}$
$L = 3.65\times 10^{-34}~J~s$
