The energy of an electron in an orbit in hydrogen atom is \(-3.4\ \text{eV}\). Its angular momentum in the orbit will be:
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For hydrogen atom:
\[
E_n=-\frac{13.6}{n^2}\text{ eV}
\]
and
\[
L=n\frac{h}{2\pi}.
\]
Always determine \(n\) from the energy first and then substitute into the angular momentum formula.