NEET Physics Refraction MCQ Question
A double convex lens has radii of curvature R1 = 20 cm and R2 = 30 cm. The refractive index of the lens material is 1.5. What is the focal length of the lens if the object is at infinity?
15 cm
20 cm
10 cm
25 cm
Correct Answer
Detailed Explanation
Using the lens maker's formula: 1/f = (n - 1)(1/R1 - 1/R2), where n = 1.5, R1 = 20 cm, R2 = -30 cm, we find f = 15 cm.
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