# Radius of bound states (Bohr)

## Homework Statement

Hi I'm having difficulty in understanding how to calculate the radius for certain situations.

for example, I have a question that asks me to calculate the radius and binding energy of muonic hydrogen.

## The Attempt at a Solution

my first instincts were to use and re-arrange the following formula
(Me v^2)/r = (e^2)/(4pi(r^2) epsilon)

re-arranging this to make r the focus and simply multiplying the electron mass by 207 to make it the muon mass.

I don't think this is correct however - seems a bit of a flaky way of doing it.

I do also have equations for the expectation values - which I presume to be the expected values for the location of the muon (and hence possibly the radius), but I'm unsure of how to apply these to the question.

I also have to apply this to other situations other than a straight hydrogen atom, so any advice would be appreciated.

Thanks