Physics - Geometrical Optics Question with Solution | TestHub

PhysicsGeometrical OpticsRefraction+ReflectionEasy2 minPYQ_2020

PhysicsEasysingle choice

A thin plano-convex lens acts like a concave mirror of focal length $0.2 m$ , when silvered on 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

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Answer:

Solution:

$F = - 0.2 m$ , $f_{m} = \infty$

$μ = 1.5$ $f_{l} = \frac{R}{(μ - 1)}, \frac{1}{f_{F}} = \frac{1}{f_{m}} - \frac{2}{f_{l}}$

$\Rightarrow F = \frac{- f_{l}}{2}$

$\Rightarrow F = - \frac{R}{2 (μ - 1)}$

$∴ - 0.2 = - \frac{R}{2 (1.5 - 1)}$

$∴ 0.2 = \frac{R}{1}$

$∴ R = 0.2 m$

Stream:JEESubject:PhysicsTopic:Geometrical OpticsSubtopic:Refraction+Reflection

⏱ 2mℹ️ Source: PYQ_2020

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