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Question

Physics Question on Atoms

The energy of an electron in an excited hydrogen atom is −3.4 eV-3.4\,eV . Its angular momentum is

A

3.72×10−34J−s 3.72\times 10^{-34}J-s

B

2.11×10−34J−s2.11 \times 10^{-34}J-s

C

1.57×10−34J−s1.57 \times 10^{-34}J-s

D

1.11×10−34J−s1.11 \times 10^{-34}J-s

Answer

2.11×10−34J−s2.11 \times 10^{-34}J-s

Explanation

Solution

Energy of electron in nth energy level in hydrogen atom =−136n2eV=-\frac{136}{n^{2}} eV Here, −13.6n2=−3.4 eV-\frac{13.6}{n^{2}}=-3.4\, eV So, n=2n=2 Angular momentum from Bohrs principle =nh2π=n \frac{h}{2 \pi} =2×6.626×10−342×314=\frac{2 \times 6.626 \times 10^{-34}}{2 \times 314} =2.11×10−34J−s=2.11 \times 10^{-34} J - s