CBSE Class 12 Physics 2022 Term 2 Outside Delhi Set 3 Solved Paper

Question : 5

Total: 5

(a) The energy of hydrogen atom in an orbit is −1.51‌eV. What are kinetic and potential energies of the electron in this orbit?
(b) The electron in a hydrogen atom is typically found at a distance of about 5.3×10−11m from the nucleus which has a diameter of about 1.0×10−15m. Assuming the hydrogen atom to be a sphere of radius 5.3×10−11m, what fraction of its volume is occupied by the nucleus?

Solution:

(a) Total energy =−1.51eV
So, Potential energy =2× Total energy
=−3.02eV
Kinetic energy =− Total energy
=1.51eV
(b) Volume of nucleus =

πR3
Volume of atom =

πR3
Fraction of volume occupied by the nucleus =

πr3

πR3

(0.5×10−15)3

(5.3×10−11)3

=8.39=8.4×10−16

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