What is the magnetic energy density (in terms of standard constant & `r` )at the centre of a circulating electron in the hydrogen atom in first orbit.(Radius of the orbit is `r`)

Answer

A, B, C, D

Explanation

`B=(mu_(0)I)/(2r)=(mu_(0)fe)/(2r)...(i) 1/(4piepsilon_(0)) e^(2)/r^(2)=(mv^(2))/r,f 2pi r=V` So
`f=sqrt((e^(2))/(4piepsilon_(0)mr))(1/(2pir))`....(ii)
Energy density=`B^(2)/(2mu_(0))`...(iii)
Solve (i),(ii)&(iii) and get