G-MS2D75B7RR

# Worksheet on Ray Optics

Q1 When a ray of light is incident normally on a plane mirror then the angle of reflection will be.

a) 0 degree

b) 90 degree

c) 180 degree

d) -90 degree

Q2 A ray is incident at 300 angle on plane mirror. What will be deviation after reflection from mirror.

a) 120 degree

b) 60 degree

c) 30 degree

d) 45 degree

Q3 A man runs towards stationary plane mirror at a speed of 15 m/s. What is the speed of his image with respect to mirror :-

a) 7.5 m/s

b) 15 m/s

c) 30 m/s

d) 45 m/s

Q4 Two plane mirrors are at 45 degree to each other. If an object is placed between them then the number of images will be

a) 5

b) 9

c) 7

d) 8

Q5 The focal length of a convex mirror is 20 cm its radius of curvature will be.

a) 10 cm

b) 20 cm

c) 30 cm

d) 40 cm

Q6 A diminished virtual image can be formed only in.

a) Plane mirror

b) A concave mirror

c) A convex mirror

d) None

Q7 The colour are characterised by which of following character of light :-

a) Frequency

b) Amplitude

c) Wavelength

d) Velocity

Q8 A plane glass slab is kept over various coloured letter; the letter which appears least raised is.

a) Blue

b) Violet

c) Green

d) Red

Q9 Critical angle of light passing from glass to air is minimum for.

a) Red

b) Green

c) Yellow

d) Violet

Q10 Which of the following is used in optical fibres.

a) T.I.R

b) Scattering

c) Diffraction

d) Refraction

Q11 ‘Mirage’ is a phenomenon due to.

a) Reflection of light

b) Refraction of light

c) T.I.R. of light

d) Diffraction of light

Q12 The angle of a glass prism is 4.5 degree and its refractive index is 1.52. The angle of minimum deviation will be:-

a) 1.5 degree

b) 2.3 degree

c) 4.5 degree

d) 2 degree

Q13 Prism angle of glass prism is 10 degree. It’s refractive index of red and violet colour is 1.51 and 1.52 respectively. Then its dispersive power will be.

a) 0.015

b) 0.020

c) 0.011

d) 0.019

Q14 Rainbow is formed due to :-

a) Scattering & refraction

b) Total internal reflection & dispersion

c) Reflection only

d) Diffraction and dispersion

Q15 Two convex lens of focal length 20 cm and 25 cm are placed in contact with each other, then power of this combination is:-

a) + 1 D

b) + 9 D

c) – 1 D

d) – 9 D

Q16 A convex lens of focal length of 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination is.

a) – 1.5 D

b) – 6.5 D

c) + 6.5 D

d) + 6.67 D

Q17 An object is put at a distance of 5 cm from the first focus of a convex lens of focal length 10 cm. If a real image is formed it’s distance from the lens will be :-

a) 15 cm

b) 20 cm

c) 25 cm

d) 30 cm

Q18 A convex lens of power P is immersed in water. How will its power change?

a) Increases

b) Decreases

c) Remains unchanged

d) Increases for red colour and decreases for blue colour

Q19 A convex lens is made up of three different materials as shown in the figure. For a point object placed on its axis, the number of images formed are.

a) 1

b) 3

c) 4

d) 5

Q20 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 :-

a) Become zero

b) Become infinite

c) Become small, but non-zero

d) Remain unchanged

Q21 Minimum and maximum distance should be for clear vision of healthy eye.

a) 100 cm & 500 cm

b) Infinite & 25 cm

c) 25 cm & 100 cm

d) 25 cm & infinite

Q22 A lens is made of flint glass (refractive index = 1.5). When the lens is immersed in a liquid of refractive index 1.25, the focal length.

a) Increases to a factor of 1.25

b) Increases to a factor of 2.5

c) Increases to a factor of 1.2

d) Decreases to a factor of 1.2

Q23 Which of the following is not due to total internal reflection?

a) Working of optical fibre

b) Difference between apparent and real depth of a pond

c) Mirage on hot summer days

d) Brilliance of diamond

Q24 If the focal length of objective lens is increased then magnifying power of :-

a) microscope will increase but that of telescope decrease.

b) microscope and telescope both will decrease

c) microscope and telescope both decrease

d) microscope will decrease but that of telescope increase.

Q25 Assertion :- 11 English alphabets do not show lateral inversion.

Reason :- If some portion of a mirror is covered, the intensity of image will increase.

a) A

b) B

c) C

d) D

Q26 Assertion :- A convex mirror is used as a driver’s mirror.

Reason :- Because convex mirror’s field of view is large and images formed are virtual, erect and diminished.

a) A

b) B

c) C

d) D

Q27 Assertion :- A star will appear to twinkle if seen from free space (say moon).

Reason :- An air bubble inside water behave like a convergent lens.

a) A

b) B

c) C

d) D

Q28 Assertion :- The twinkle of stars is due to the fact that refractive index of the earth’s atmosphere fluctuates.

Reason :- In cold countries, the phenomena of looming (i.e ship appears in the sky) takes place, because

refractive index of air decreases with height.

a) A

b) B

c) C

d) D

Q29 Assertion :- The image formed by total internal reflections are much brighter than those formed by mirrors or lenses.

Reason :- There is no loss of intensity in total internal refection.

a) A

b) B

c) C

d) D

Q30 Assertion :- Diamond glitters brilliantly.

Reason :- Diamond does not absorb sunlight.

a) A

b) B

c) C

d) D

Q31 Assertion :- The sun appears some time before the actual sun-rise.

Reason :- Because of the refraction through the different layers of atmosphere.

a) A

b) B

c) C

d) D

Q32 Assertion :- A beam of white light when passed through a hollow prism, cannot give spectrum.

Reason :- Because refractive index of air inside and outside the prism is same, so no refraction and hence no deviation will take place.

a) A

b) B

c) C

d) D

1) a

2) a

3) b

4) c

5) d

6) c

7) a

8) d

9) d

10) a

11) c

12) b

13) d

14) b

15) b

16) a

17) d

18) b

19) b

20) b

21) d

22) b

23) b

24) d

25) c

26) a

27) d

28) b

29) a

30) b

31) a

32) a