Positive rays produce luminescence upon striking________________?
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Answer: D. ZnS
Explanation
Positive rays produce bright luminescence and scintillation when they strike a zinc sulfide screen. Zinc sulfide acts as an efficient phosphor that converts kinetic energy from moving ions into visible light. Detecting positive rays in early particle experiments relied heavily on this specific luminescent target material. Positive rays, also known as canal rays, consist of positive ions streaming through holes in cathode ray tubes. Zinc sulfide phosphors emit photons when high-speed particles transfer energy to their crystalline lattice electrons. Eugen Goldstein discovered canal rays in modified discharge tubes containing perforated cathode plates.
Option A is incorrect because silver nitrate plates are used for chemical testing rather than ray detection. Option B is wrong because silver chloride plates darken upon light exposure instead of emitting bright luminescence. Option C is incorrect because zinc oxide lacks the specific phosphor efficiency required for canal ray detection.
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