WB JEE 2018 | Geometrical Optics Question 17 | Physics

WB JEE 2018

MCQ (Single Correct Answer)

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WB JEE 2018 Physics - Geometrical Optics Question 11 English

Two identical equiconvex lenses, each of focal length f are placed side by side in contact with each other with a layer of water in between them as shown in the figure. If refractive index of the material of the lenses is greater than that of water, how the combined focal length F is related to f?

F > f

$${f \over 2} < F < f$$

$$F < {f \over 2}$$

F = f

WB JEE 2018

MCQ (Single Correct Answer)

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There is a small air bubble at the centre of a solid glass sphere of radius r and refractive index $$\mu$$. What will be the apparent distance of the bubble from the centre of the sphere, when viewed from outside?

$${r \over \mu }$$

$$r\left( {1 - {1 \over \mu }} \right)$$

Zero

WB JEE 2017

MCQ (Single Correct Answer)

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The ratio of the diameter of the sun to the distance between the earth and the sun is approximately 0.009. The approximate diameter of the image of the sun formed by concave spherical mirror of radius of curvature 0.4 m is

4.5 $$ \times $$ 10^$$-$$6 m

4.0 $$ \times $$ 10^$$-$$6 m

3.6 $$ \times $$ 10^$$-$$3 m

1.8 $$ \times $$ 10^$$-$$3 m

WB JEE 2017

MCQ (Single Correct Answer)

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A point object is held above a thin equiconvex lens at its focus. The focal length is 0.1 m and the lens rests on a horizontal thin plane mirror. The final image will be formed at

infinite distance above the lens

0.1 m above the center of the lens

infinite distance below the lens

0.1 m below the center of the lens

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