# Homework Help: Calculate the orbital period

1. Mar 2, 2012

### Firben

1)Use the bohr model, calculate the orbital period in eachlevel(n=1,2,3)

2) the average lifetime of the first excited level of a hydrogen atom is 1.0 10^-8 s. In the bohr model, how many orbits does an electron in the n=2 level complete before returning to the ground level?

2. Relevant equations

E(n) = -13.60/(n^2) (1)
λ = hc/(E(2)-E(1)) (2)
f = c/λ (3)
f = (E(1)-E(2))/h (4)
T = 1/f (5)
h = 6.626*10^-31 J*s
r(n) = ε(n^2*h^2)/(π*m*e^2) (6)
m=9.109*10^-19 kg
ε(0) = 8.85 * 10^-12 C^2/N*m^2
e = 1.60*10^-19 C

3. The attempt at a solution

After i have numerically inserted the values in the equations (4),(1) and (5) i got i to be
3.42*10^-16 s, 3.2466*10^-16s and 4.10*10^-16 is that correct ?

In 2) should i calculate circumference to begin with ?