1. The problem statement, all variables and given/known data According to the classical nature of the hydrogen atom an electron in a circular orbit of radius 5.3*10^-11m around a proton fixed at the centre is unstable. If it is true, how long would it take for the electron to collaspse into the proton? 2. Relevant equations There is a hint: "Use integral calculus to solve the classical expression for radiation from an accelerated charge" 3. The attempt at a solution I really don't know where to start... can anyone care to tell me what is the "classical expression for radiation"?