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Point of the Question

When we advanced to the junior high school, we studied electrical energy in science. Science was one of my favorite courses, but one day, my interest was changed to something unpleasant. During the lesson about the principle of lightning strikes, I asked the teacher why the electricity charged in the sky runs into the earth and dose not discharge in mid air. The teacher's explanation was quite clear, saying the electricity charged in the sky is plus while the earth is minus.

I wondered, then, why the electricity charged in the sky is always plus, and why the earth is minus. But I missed the chance to ask further question about it. As a result of lack of such basic understanding, and with the lesson advancing to alternating currents, I became more weak in it. In other words, the teacher did not understand the true point of my question. It is funny that the question is still unsolved in my mind even at this late stage.

Also, during the lesson of mathematics, the teacher asked us why the tempo of music recorded on a disk plate does not become quicker following the needle moving into the central part of the disk. I could not understand what the question meant, but in the class, there were several students pondering the same question as the teacher's, and the class became a little noisy from the whispering. Somebody answered that it is because the music is reborn in the same speed as it was recorded, therefore, the tempo of music has no relation to the time of the needle's movement traveling around in a circle. Then, I understood the real meaning of the teacher's question.

It seems that this kind of discrepancies happens rather frequently in our daily lives.