What is the approximate ratio of the velocity of an electron in the ground state of a hydrogen atom

Question

What is the approximate ratio of the velocity of an electron in the ground state of a hydrogen atom to the velocity of light in a vacuum ($c$)?

Professor PC Thomas Classes · Answer

The velocity of an electron in the ground state of a hydrogen atom is roughly $2.18 	imes 10^6$ m/s, which is approximately $c/137$.