Lenard rays

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Rays emanating from the outer surface of a plate composed ofany material permeable by cathode rays, as aluminium, which forms aportion of a wall of a vacuum tube, or which is mounted within thetube and exposed to radiation from the cathode. Lenard rays aresimilar in all their known properties to cathode rays. So called fromthe German physicist Philipp Lenard (b. 1862), who first describedthem.