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Light from a point source in air falls on a spherical glass surface. If `mu = 1.5`, and radius of curvature `= 20 cm`, the distance of light source from the glass surface is `100 cm` , at what position will the image be formed ? (NCERT Solved Example)

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Here, `R = PC = + 15//2 cm`
`nu_(2) = 4//3, mu_(1) = 1`
For a parallel beam of light, `mu = oo`. Fig.

The beam diverges on refraction and appears to come from `I`.
`PI = v = ?`
As refraction occurs from denser to rarer medium, therefore,
`-(mu_(2))/(u) + (mu_(1))/(v) = (mu_(1) - mu_(2))/(R )`
`-(4)/(3 xx oo) + (1)/(v) = (1 - 4//3)/(15//2) = -(2)/(45)`
`v = -(45)/(2) = -22.5 cm`
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