Mon April 25, 2011 By:

A fluorescent lamp of length 1 m is placed horizontal at a depth of 1.2 m below a ceiling. A plane mirror of length 0.6 m is placed below the lamp parallel to and symmetric to the lamp at a distance 2.4 m from it. The length of the reflected patch on the ceiling is (A) 3 m (B) 4 m (c) 7 m (D) none of these

Expert Reply
Mon May 16, 2011
Here, let CD be the fluorescent lamp placed below the ceiling at a depth of 1.2 m.
Let AB be the plane mirror placed below the lamp and PQ be the reflected patch on the ceiling.
By symmetry of triangles, MN = 0.2 m
PE=1m and QF = 1m
Therefore, PQ = 1+1+1 = 3m
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