CRT 7(CBSE 10th)

An object is placed 20 cm in front of a plane mirror. The mirror is moved 2 cm towards the object. The distance between the positions of the original and final images seen in the mirror is:

(a)  

A concave mirror produces a magnification of +4. The object is placed:

• At the focus

• Between focus and centre of curvature

• Between focus and pole

• Beyond the centre of curvature

A ray of light passes from a medium X to another medium Y. No refraction of light occurs if the ray of light hits the boundary of medium Y at an angle of:

• 120^o

• 90^o

• 45^o

• 0^o

A student does the experiment on tracing the path of a ray of light passing through a rectangular glass slab for different angles of incidence. He can get a correct measure of the angle of incidence and the angle of emergence by following the labelling indicated in figure:

• A

• B

• C

• D

Focal length of plane mirror is

• At infinity

• Zero

• Negative

• None of these

In optics an object which has higher refractive index is called

• Optically rarer

• Optically denser

• Optical density

• Refractive index

The number of images observable between two parallel mirrors is :

• 1

• 2

• 4

• Infinity

Total internal reflection of light is possible when light enters from :

• Water to air

• Air to water

• Vacuum to air

• Air to glass

A man runs towards the plane mirror at 2 m/s. The relative speed of his image with respect to him will be:

• 4 ms⁻¹

• 2 ms⁻¹

• 8 ms⁻¹

• 10 ms⁻¹

Refractive index:

• Depends on the wavelength of light used to measure

• Is actual property of the substance

• Depends on the angle of incidence

• None of these