In this ppt you can learn about the light first by recall second by the different type of questions which help you in board as well as competitive exam

1. LIGHT
The Reason behind the visibility

2. Let’s Recall
What we have learn------

3. Explain….
1. Incident Ray
2. Reflected Ray
3. Incident angle
4. Reflected angle
5. Laws of Reflection

4. Explain this phenomenon:

7. Extra knowledge:

8. MCQ:
1. A small hole P is made in a piece of cardboard. The hole is illuminated by a
torch. The pencil of light coming out of the hole falls on a mirror. The angle of
incident is 90 degree. What will be the angle of reflection:
a) 45
b) 90
c) 95
d) None of these

9. 2. How many times is a ray of light reflected by two plane mirrors placed parallel
and facing each other?
a) Infinite number of times
b) Two times
c) Three times
d) None of the above

10. 3. A small hole P is made in a piece of cardboard. The hole is illuminated by a torch
as shown in Fig. The pencil of light coming out of the hole falls on a mirror.
At which point should the eye be placed so that the hole can be
seen?
(a) D (c) C
(b) B (d) A

11. 4. A tiny mirror M is fixed on a piece of cardboard placed on a table. The cardboard
is illuminated by light from a bulb. The position of eye with respect to position of
bulb is shown in Fig. A, B, C and D. In which position mirror will be visible?
a. A c. C
b. B d. D

12. 5. Light is falling on surface S1, S2, S3 as shown in Fig.
Surfaces on which the angle of incidence is equal to the angle of reflection is/are
(a) S1 only
(b) S2 and S3
(c) S1 and S2 only
(d) all the three surfaces

13. 6. Image formed by a plane mirror is
(a)Virtual, behind the mirror and enlarged
(b)Virtual, behind the mirror and of the same size as the object
(c)Real at the surface of the mirror and enlarged
(d)Real, behind the mirror of the same size as the object

14. MCQ solution:
1. (b)
2. (a)
3. (d)
4. (a)
5. (d)
6. (b)

15. Short Answer Type:
1. Explain the process which enables us to perceive motion in a cartoon film.
2. How is the phenomenon of reflection used in making a kaleidoscope? What
are the applications of a kaleidoscope?
3. Fig. shows the word REST written in two ways in front of a mirror. Show how
the word would appear in the mirror.

16. 4. There is a mistake in each of the following ray diagrams given as
Fig. a, b, and c. Make the necessary correction (s). Explain it

17. Solution:
1. The cartoon film we see is actually the projection of static pictures on the screen
in a specific order. Usually the static pictures are shown in a sequence at the
rate of 24 pictures per second one after the other giving us the perception of
movement.
2. The kaleidoscope gives a number of images formed by reflection from the
mirrors inclined to one another. Designers and artists use kaleidoscope to get
ideas for new patterns to design wallpapers, Jewellery and fabrics.

18. Long Answer Type:
1. Boojho planned an activity to observe an object A through pipes as shown in Fig. so
that he could see objects which he could not directly see.
a) How many mirrors should he use to see the objects?
(b) Indicate the positions of the mirrors in the figure.
(c) What must be the angle with respect to the incident light at
which he should place the mirrors?
(d) Indicate the direction of rays in the figure.
(e) If any of the mirrors is removed, will he be able to see the objects?

19. 2. Differentiate between regular and diffused reflection. Does diffused reflection
mean the failure of the laws of reflection?
3. State the laws of reflection?

20. Solution:
1. (a) Three
(b)
(c) 450
(e) No, he will not be able to see the objects.

21. Regular Reflection
1.It takes place from a smooth place.
2.Reflected rays moves in a particular direction.
3. Example: Reflection by plane mirror.
Diffused Reflection
1. It takes place from a rough surface.
2. Reflected rays scattered in random directions.
3. Reflection by road surface.
Answer3.
Laws of reflection:
The angle of incidence is always equal to the angle of reflection.
The incident ray, the reflected ray and the normal to the surface at the point of incidence lie in the
same plane.