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Showing results for tags 'electromagnetic waves'.
If we swing a glass plate like a hand-held fan, then we cause an alternating current in the air, that is, we cause longitudinal waves in it. If we swing it pretty fast, then we cause sound waves as well (which are also longitudinal waves). If we now rub the glass plate with a woolen cloth, then the plate is electrified. If swing it again, we cause besides the air- and the sound-waves, also electromagnetic waves, which are also longitudinal waves. • • • • • I will jump for a moment to another question, to the one what an electric current is (for more details please see "What is electric cur