12th Physics Chapter 6 Optics - one marks online Test - Tamilnadu state board

12th Physics Chapter 6 Optics - MCQ online Test - Tamilnadu state board

• Class     : 12th standard
• Subject : physics
• Lesson  : 6
• Topic.    : Optics
• Medium : English
• Board.    : Tamilnadu state board

1.

The speed of light in an isotropic medium depends on,

(a) its intensity

(b) its wavelength

(c) the nature of propagation

(d) the motion of the source w.r.to medium

2.

A rod of length 10 cm lies along the principal axis of a concav e mirror of focal length 10 cm in such a way that its end closer to the pole is 20 cm away from the mirror. The length of the image is,

(a)2.5cm

b)5cm

C)10cm

d)15cm

3.

An object is placed in front of a convex mirror of focal length of/and the maximum and minimum distance of an object from the mirror such that the image formed is real and magnified

(a) 2ƒ and c

(b) c and ∞

(c) ƒ and O

(d) None of these

4.

For light incident from air onto a slab of refractive index 2. Maximum possible angle of refraction is

a)30º

b)45º

c)60º

d)90º

5.

If the velocity and wavelength of light in air is Va and λa and that in water is Va and λw, then the refractive index of water is,

a)`frac { V _w }{ V _ a }`

b)`frac { V _ a }{ V _ w }`

c)`frac { λ _ w }{ λ _ a }`

d)`frac { V _ a \lambda }{ V _ w \lambda _ w }`

6.

Stars twinkle due to

(a) reflection

(b) total internal reflection

c) refraction

(d) polarisation

7.

When a biconvex lens of glass having refractive index 1.47 is dipped in a liquid, it acts as a plane sheet of glass. This implies that the liquid must have refractive index,

(a) less than one

(b) less than that of glass

(c) greater than that of glass

(d) equal to that of glass

8.

The radius of curvature of curved surface at a thin planoconvex lens is 10 cm and the refractive index is 1.5. If the plane surface is silvered, then the focal length will be,

a)5cm

b)10cm

c)15cm

d)20cm

9.

An air bubble in glass slab of refractive index 1.5 (near normal incidence) is 5 cm deep when viewed from one surface and 3 cm deep when viewed from the opposite face. The thickness of the slab is,

a)8cm

b)10cm

c)12cm

d)16cm

10.

A ray of light travelling in a transparent medium of refractive index n falls, on a surface separating the medium from air at an angle of incidents of 45º. The ray can undergo total internal reflection for the following n,

(a) n= 1.25

(b) n = 1.33

(c) n= 1.4

(d) n= 1.5

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