image tag: franck-hertz, orientation: horizontal, image quantity: 5

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physics, light, triode, helium, quantum physics, franck-hertz
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radio, frequency, hertz, technology, instrument of Measurement
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tachometer, hertz, speed, gauge, revolutions, instrument of Measurement, equipment
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doors, school, input, hamburg, heinrich hertz school, portals, stairs
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hamburg, tv tower, germany, sky, radio tower, city, tower