A symmetric double convex lens is cut in two equal parts by a plane containing the principal axis. If the power of the original lens was 4 D,
A symmetric double convex lens is cut in two equal parts by a plane containing the principal axis. If the power of the original lens was 4 D, the power of a divided lens will be
(a) 2 D
(b) 3 D
(c) 4 D
(d) 5 D.
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The correct answer is (c) 4 D
EXPLANATION:
The plane containing the principal axis will cut the lens in two semicircular pieces and each piece will be a lens having the same radius of the curvatures. Hence each of the pieces will have the same focal length and the same power. Thus the option (c).
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