Question

A convex lens of power 3 D is held in contact with a a concave lens of power -1 D. A parallel beam of light is made to fall on the combination. At what distance from the combination will the beam get focused *​

Answer 1

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• Total Power = 2D
• Focal Length = 1/2 = 0.5m = 50cm
• When a Ray of light parallel to A Convex lens (f is +ve) hits the lens then Image is formed at focus
• So Beam will be Focussed on Focus At 50cm