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Scientific Puzzle
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This is a most interesting scientific puzzle. I had been unsuccessful in getting my point over during a discussion with a university physics professor, so I posed the following puzzle, which I asked him to solve. Although it seemed to me to be comparatively simple, he refused, saying it was a "trick". In my opinion, the rather simple puzzle described below can be solved with just a basic knowledge of physics.

Puzzle: In order to solve this problem, one must have a basic knowledge of the properties of an electric dipole (defined by Coulomb's Law), which is simply two separated positive and minus charges in open space, as shown below:

The distances from each of the two electric charges to the origin are equal, and therefore the distances from the charges to any point in the y-z plane are also equal. At any point to the right of the y-z plane the field is negative, and at any point to the left it is positive. Therefore, the field level is zero everywhere in the y-z plane.

I now pose the question as to what happens to the shape of the zero-field level planar shape (the y-z plane) as the entire system is moved toward the left? It is not necessary to consider exact values, just the general shape of the plane wave, or even just a vertical line within it, in the far field. Considering just the vertical line through the origin, does its shape change, or does it remain straight? If it changes shape, then plot the general shape at some short time, T, after the system is moved. For convenience and simplicity, limitations of inertia need not be imposed (start and stop times). If you have difficulty in visualizing the situation, make a guess. The import of the results are highly significant.

Conditions and Suggestions : Simply move the dipole (both charges) directly to the left at a uniform velocity and neglect the rise and fall times. The distance between the charges does not change. Does the shape of the plane (or vertical line in the plane) bend, or does it stay straight? If it bends, then think about how it bends. Hint: consider the limitations of the speed of light and the conditions in the far field. You may be surprised at what you learn from this exercise!

An Expert's Answer: Another physicist, claimed that the Lorentz force must be used to solve this problem. That is not true. The Lorentz force describes the effects on the electron moving in magnetic field. In this case, we assume the charges to be moving in a straight line in open space. The problem, as posed, does not therefore involve the Lorentz force on the charges. Coulomb's law applies, and it is the most reliable and thoroughly proven physics model in existence.

Suggestion: It is only necessary to consider the one equipotential vertical line in the y-z plane in order to see what is happening. All other lines in the y-z plane behave similarly. The choice of using a straight line is to be able to see changes in shape. You may be surprised at what you learn from this exercise! It is extremely important due to the consequences presented by the shape of the moving wave.

Recommendations: If you are sure you have the answer, please let me know your result, and we will comment on it. If you have trouble in finding the answer, see what your scientific friends come up with and/or contact me for an answer. Physics students may also want to pose this problem to their professors. If needed, scroll down to the clue below:











Clue: The results of this exercise also correlate to transverse (non-spherical) waves of electromagnetic radiation, which move at the speed of light. Proven electromagnetic radiation models have been in existence for at least 70 years. The model of electromagnetic radiation can be graphed, and the shape of the waves in the far field produce consistent patterns that have a certain resemblance to those of the above moving dipole (see my paper on electromagnetic radiation). If there is sufficient response to this puzzle, I will expand this page in accordance with the responses. Send questions using this link.


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