Forged documents are detected by
(A) ultraviolet rays
(B) infra-red rays
(C) beta rays
(D) gamma rays
Correct Answer : ultraviolet rays
Question Asked : SSC Combined Matric Level (Pre) Exam 2002
Explanation : Old postcards, books, signs, photos and other paper products made before the late 1930s rarely glow under a black light. Chemical bleaches and dyes used in modern papers will fluoresce under ultraviolet light. Knowing this helps to detect forged documents and distinguish reproductions in all types of ephemera.
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Tags : Physics
