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Today I enjoyed a first tutoring session with an intelligent young student who wanted to understand better how a speaker works. She had built one as part of a class assignment and it worked! The principle of the speaker is a based on physics, namely, the force between two magnets. I explained how a time-varying electrical current from the stereo system flows through a wire wrapped in the form of a coil, and this coil then produces a time-varying magnetic field. This field acts on a permanent magnet, alternately pushing and pulling on it according to which way the current was flowing. This time-varying causes the permanent magnet to vibrate, and a diaphragm attached to the permanent magnet then also vibrates, generating a wave in the air that we hear as sound. It is really nice to clarify something in physics, science, math and see how the student goes from little or no understand to a good understanding. This is the part of teaching that I really enjoy and I look forward... read more

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