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  • 1Scale (map) — The scale of a map is defined as the ratio of a distance on the map to the corresponding distance on the ground. If the region of the map is small enough for the curvature of the Earth to be neglected, then the scale may be taken as a constant… …

    Wikipedia

  • 2Acousto-optics — is a branch of physics that studies the interactions between sound waves and light waves, especially the diffraction of laser light by ultrasound or sound in general.IntroductionOptics has had a very long and full history, from ancient Greece,… …

    Wikipedia