JEE Main 2016 · 10 Apr · Shift 1 · Physics Q19

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PhysicsSingle correct+4 / -1Question 19 of 90

A hemispherical glass body of radius 10 cm and refractive index 1.5 is silvered on its curved surface. A small air bubble is 6 cm below the flat surface inside it along the axis. The position of the image of the air bubble made by the mirror is seen :

A glass hemisphere of radius 10 cm, flat face up, silvered on its curved surface; an air bubble O lies on the axis 6 cm below the flat face.

14 cm below flat surface

30 cm below flat surface

20 cm below flat surface

16 cm below flat surface

Answer and worked solution

Official answer: C

The mirror (curved surface) has R = 10 cm, f = 5 cm, and the bubble is 4 cm from its pole. Then $\frac1v=-\frac15+\frac14$ gives v = 20 cm behind the mirror (virtual), i.e. 30 cm below the flat surface. Seen through the flat surface, it appears at $\frac{30}{1.5}=20$ cm below it.

Topics:Spherical mirrors Reflection and plane mirrors

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JEE Main 2016 · 10 Apr · Shift 1, Physics question 19