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Question
Assertion :A plano convex lens is split into two parts by a plane perpendicular to the principle axis. The focal length of the part forming a plano convex lens will be same as before. Reason: Focal length of lens depends on the radii of curvature of two surfaces.
Assertion :A plano convex lens is split into two parts by a plane perpendicular to the principle axis. The focal length of the part forming a plano convex lens will be same as before. Reason: Focal length of lens depends on the radii of curvature of two surfaces.
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Solution
The correct option is D Both Assertion and Reason are incorrect
The focal length f∝1t where t is the thickness of the lens.
Since the plano convex lens is split into two parts by a plane perpendicular to the principle axis, thickness of each split part is t2. Hence the focal length of each half becomes 2f
The focal length f∝1t where t is the thickness of the lens.
Since the plano convex lens is split into two parts by a plane perpendicular to the principle axis, thickness of each split part is t2. Hence the focal length of each half becomes 2f
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