A thin plano-convex lens, acts like a concave mirror of focal length 0.2 m, when silvered from its plane surface. The refractive index of the material of the lens is 1.5. The radius of curvature, of the convex surface, of the lens will be
Answers
The radius of curvature of the curved surface of the lens will be 20 cm
Explanation:
The refractive index of the material of the lens, μ = 1.5
=> Using the equation,
1/F = 2(μ₂/μ₁) / R₂ - 2(μ₂/μ₁) - 1 / R₁
=> But for plano - convex lens, R₂ = ∞
1/-10 = 2(1.5)/∞ - 2(1.5) - 1 / R₁
1/-10 = - 2(1.5) - 1 / R₁
1/-10 = - (3 - 1) / R₁
1/-10 = - 2 / R₁
R₁ = -2 * -10
∴ R₁ = 20 cm
Thus, the radius of curvature of the convex surface will be 20 cm.
Learn more:
Q:1 A plano-convex lens, when silvered at its plane surface is equivalent to a concave mirror of focal length 28cm.when its curved surface is silvered and the plane surface not silvered,it is equivalent to a concave mirror of focal length 10cm,then the refractive index of the material of the lens is ?
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Q:2 A double concave lens with refractive index (n)=1.5 is kept in the air. It's two spherical surfaces have radii R1 =20cm and R2=60cm.Find the focal length of the lens. write the characteristics of the lens.
Click here : https://brainly.in/question/1135724
Answer:The refractive index of the material of the lens, μ = 1.5
=> Using the equation,
1/F = 2(μ₂/μ₁) / R₂ - 2(μ₂/μ₁) - 1 / R₁
=> But for plano - convex lens, R₂ = ∞
1/-10 = 2(1.5)/∞ - 2(1.5) - 1 / R₁
1/-10 = - 2(1.5) - 1 / R₁
1/-10 = - (3 - 1) / R₁
1/-10 = - 2 / R₁
R₁ = -2 * -10
∴ R₁ = 20 cm Ans...
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Explanation: