N Bohr’s model of H-atom. the radius of the first electron orbit is 0.53 A

CBSE Class 12 CBSE Class 12 Physics
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1

In Bohr’s model of H-atom. the radius of the first electron orbit is 0.53 A. What will be the radius of the third orbit and the first orbit of singly ionised helium atom?

2

Radius of nth Bohr’s orbit =
Again , r ∝ 1/z
{ r }_{ He+ } / Rhe =
{ Z }_{ H+ } / Zhe+
For hydrogen , Z=1 and for helium , Z=2