Question

In hydrogen a atom, an electric is revolving in the orbit of radius 0.53 ̇ with 6.6x1015 radiations/s.
Magnetic field produced at the centre of the orbit is
A) 0.125 Wb/m²
B) 1.25 Wb/m²
C) 12.5 Wb/m²
D) 125 Wb/m²

Answer 1

Simply use formula
B=vI/2R
v is frequency

see the current due to an electron revolving with the frequency if 6.6x1015 r.p.s is same as that when 6.6x1015 electrons move around the orbit in a second.

hence the total current in the orbit is 6.6 x 1015 x 1.6 x10-19 = 10.56 x 10-4 A

now simply put the values in formula
B=12.5 T