Light , Human Eye and Colourful world

In the given diagram, three rays of light pass through focal point F1 to the converging lens, placed along the vertical line. Which of the following is correct regarding this?

• A) The speed of light rays decreases when they enter the converging lens.

• B) The speed of light rays decreases when they leave the converging lens.

• C) The speed of light rays increases when they enter the converging lens.

• D) The speed of light rays remains same while entering or leaving the converging lens.

A ray of light passing through a semicircular block from air is shown below. Consider the given figure and select the correct option that correctly identifies the true (T) and false (F).

(i) There is no change in the direction of the ray at P because the light ray incident on the semicircular block at 90∘.

(ii) As light rays enter the semicircular block, their frequency remains the same.

(iii) The wavelength of light rays as it enters the block decreases.

(iv) The speed of light as it enters the block increases.

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A man standing at a position X in front of a plane mirror, a distance of y metre from the mirror as shown in figure. When the man moves 5 m away from the mirror, the new distance between the man and his image becomes 20 metre. What is the value of y?

•    A) 5 m 

• B) 10 m

• C) 20 m

• D) 40 m

To produce an image by a convex lens, at the position shown (see figure) the object is needed to be placed

• A) Between Y and O

• B) At Y

• C) Between X and Y

• D) At X

When two plane mirrors are placed parallel and facing each other and an object is kept in between them, we get infinite images. But actually only a few images are visible because the intensity of the image is

• A) Increased after each reflection

• B) Decreased after each reflection

• C) Always constant

• D) None of these

Which of the following options is correct in case of a concave mirror?

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Which of the following correctly depicts reflections in case of plane mirrors inclined at

40?

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The image of an extended object placed in front of a concave mirror is formed at a distance of 40 cm from the object. If the image is 3 times bigger than the object, the magnitude of focal length of the mirror is

• A) 15 cm

• B) 10 cm

• C) 20 cm

• D) 5 cm

"HOTS"

Two plane mirrors A and B are aligned parallel to each other as shown in the figure.

A light ray is incident at an angle 30∘ at a point just inside one end of A.

The plane of incidence coincides with the plane of the figure.

The maximum number of times the ray undergoes reflections (including the first one), before it emerges out, is

• A) 28

• B) 30

• C) 32

• D) 34

Direction: Read the passage carefully and answer the following question. A beam of white light falling on a glass prism gets split into seven colours marked 1 to 7 as shown in figure.

Which of the following statements is correct?

• A) The colour at position marked 5 is similar to the colour of gold metal.

• B) The colour at position marked 2 has longer wavelength than 1.

• C) The colour at position marked 7 is violet.

• D) The colour at position marked 5 has higher speed than 1.