# Electricity and revolutions per second

#### abeltyukov

Hi,

1. Homework Statement

In a simple model of the hydrogen atom, the electron moves in a circular orbit of radius 0.053 nm around a stationary proton. How many revolutions per second does the electron make?

2. Homework Equations

F = (kq1q2)/r^2 = (mv^2)/r

v = wr

3. The Attempt at a Solution

Charge of electron = -1.602 x 10^-19 C
Charge of proton = 1.602 x 10^-19 C
Mass of electron = 9.109 x 10^-31 kg

[(8.999 x 10^9)(1.602 x 10^-19)(1.602 x 10^-19)] / (0.053 x 10^-9) = (mv^2)/r

v = 0.002187 m/s

v = wr

0.002187 = w(0.053 x 10^-9)

w = 41267720.67

Any ideas on what I am doing wrong? Thanks!
1. Homework Statement

2. Homework Equations

3. The Attempt at a Solution

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#### Kurdt

Staff Emeritus
Gold Member
You may find it easier to work algebraically until the last moment and then plug the numbers in. With the equations you have you want to rearrange of the angular speed (omega). Once you find omega you will then need to find the frequency. Do you know the equation to find the frequency?

#### abeltyukov

Can you give me an example please? Thanks!

Staff Emeritus