Imagine a Hydrogen atom to consist of a single proton as a nucleus and a single electron, which orbits the proton in a circular path. If the separation of the electron from the proton is one Angstrom, how fast is the electron moving to remain in a stable orbit? How much time does it take for the electron to complete one orbit? If the kinetic energy of the electron decreases by a small amount with every full revolution, then what will be the radius of the orbit when it has lost half of its original kinetic energy?