# CBES Board Class 12/CBES Board(Class 12-Physics)MCQ Questions with Answers(Chapter 9 Ray Optics and Optical Instruments) Sample Test,Sample questions

## Question: `A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will`

1.become zero

2.become infinite

3.become small, but non-zero

4.remain unchanged

Posted Date:-2021-02-02 14:11:47

## Question: `A rod of length 10 cm lies along the principal axis of a concave mirror of focal length 10 â€™em in such a way that its end closer to the pole is 20 cm away from the mirror. The length of the image is`

1.10 cm

2.15 cm

3.2.5 cm

4.5 cm

Posted Date:-2021-02-02 14:11:47

## Question: `An astronomical refractive telescope has an objective of focal length 20 m and an eyepiece of focal length 2 cm. Then`

1.the magnification is 1000

2.the length of the telescope tube is 20.02 m

3.the image formed of inverted

4.all of these

Posted Date:-2021-02-02 14:11:47

## Question: `An under-water swimmer cannot see very clearly even in absolutely clear water because of`

1.absorption of light in water

2.Â scattering of light in water

3.reduction of speed of light in water

4.change in the focal length of eye lens

Posted Date:-2021-02-02 14:11:47

## Question: `For a total internal reflection, which of the following is correct?`

1.Light travels in water only.

2.Light travels from rarer to denser medium.

3.Light travels from denser to rarer medium.

4.Light travels in air only.

Posted Date:-2021-02-02 14:11:47

## Question: `Mirage is a phenomenon due to`

1.refraction of light

2.reflection of light

3.total internal reflection of light

4.Â diffraction of light.

Posted Date:-2021-02-02 14:11:47

## Question: `Two beams of red and violet color are made to pass separately through a prism (angle of the prism is 60Â°). In the position of minimum deviation, the angle of refraction will be`

1.30Â° for both the colors

2.greater for the violet color

3.greater for the red color

4.equal but not 30Â° for both the colors

Posted Date:-2021-02-02 14:11:47

## Question: `Two lenses of focal lengths 20 cm and â€“ 40 cm are held in contact. The image of an object at infinity will be formed by the combination at`

1.10 cm

2.20 cm

3.40 cm

4.infinity

Posted Date:-2021-02-02 14:11:47

## Question: `Which of the following colours of white light deviated most when passes through a prism?`

1.Red light

2.Violet light

3.Yellow light

4.Both (1) and (2)

Posted Date:-2021-02-02 14:11:47

## Question: `Which of the following forms a virtual and erect image for all positions of the object?`

1.Concave lens

2.Concave mirror

3.Convex mirror

4.Both (1) and (3)

Posted Date:-2021-02-02 14:11:47

## More MCQS

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