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Name: James
Status: student
Age: 30s
Location: N/A
Country: N/A
Date: 8/31/2004

RE: Electron orbital paths around a nucleus in a gravitational field. Do electrons maintain a "constant" circular path around a nucleus when travelling in the Y plane, I.E. vertically. or does a "Kepler" effect start up where it would tend to accelerate towards the lower portion of its orbit (due to gravity) and then slingshot back up?

The force of gravity depends upon the masses of the objects. Electrons and atomic particles have such small masses gravity has a negligible effect on their behavior under ordinary conditions. Electromagnetic forces and quantum mechanics determine the behavior of atomic and subatomic particles.

Vince Calder

The gravitational force acting on an electron is so small that it is impossible to produce any observable effect, except perhaps in the bowels of a black hole.

To illustrate, the gravitational force between the electron and the proton in a hydrogen atom is approximately 1.0E-44 times smaller than the electrical force. That's 0.000...0001 times, where there are 43 zeros between the decimal point and the 1.

It is possible to have an analogous effect to the gravitational effect you described by imposing a very strong electric field on the atom. This is called the Stark Effect. It causing broadening and small shifts in the spectral lines emitted by the atom. Do a web search on "stark effect" for more information.

Best, Dick Plano...

Gravity effects are so much smaller than the other forces keeping an atom together that on this scale, this small an object, they do not matter. it is only when things get really big, with all the +/- charge effects cancelling, but gravity continuing to "add up" that gravity matters.

Steve Ross


A true electron orbit is not nearly so simple as a circle or ellipse. According to quantum physics, there is no set motion. We can talk about an average radius of an orbit. We can talk about the angular momentum and energy of an orbit. We can talk about how much of the orbit is in the horizontal plane. In reality, the electron's orbit is not any specific motion. It bounces all over the place. Higher energy electrons have a greater average radius. Different electrons have different angular momentums. Exact path cannot be determined.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College

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