1. STD. :- VIII SUB. :- G.SCIENCE PRESNTED BY, Mr. MANISH RAMCHANDRA AGRE K. E. S. ENGLISH MEDIUM SECONDARY SCHOOL, MAHAD, RAIGAD. GUIDED BY, Miss. JYOTI SATHE

2. Lesson No.- 7.

3. Things that are invisible in dark become visible because of light. We see things around us because of light.

4. NATURAL SOURCES OF LIGHT ARTIFICIAL SOURCES OF LIGHT

5. NATURAL SOURCES OF LIGHT THE SUN MAIN SOURCE OF LIGHT. OTHER STARS IN THE SKY.

6. ARTIFICIAL SOURCES OF LIGHT ELECTRIC BULBCANDLES TUBELIGHTS GASLIGHTS

7. EXTENDED SOURCE OF LIGHT Light rays come out from all points on the surface of bulb. Such an electrical lamp is called an Extended source of light.

8. POINT SOURCE OF LIGHT The rays coming out from a single point form a beam of light.

9. Screen Penumbra Umbra Shadow cast using a extended source object

10. Screen Umbra Shadow cast using a point source object

11. The turning back of the rays of light after falling a surface is called the reflection of light.

13. INCIDENT RAY A ray falling on surface is called an incident ray.

14. POINT OF INCIDENCE The point at which a ray falls on a surface is called the point of incidence.

15. NORMAL A line perpendicular to the surface at the point of incidence is called a normal.

16. REFLECTED RAY An incident ray gets reflected from the surface. The ray after reflection is called reflected ray.

17. ANGLE OF INCIDENCE The angle the incident ray makes with the normal is called the angle of incidence.

18. ANGLE OF REFLECTION The angle the reflected ray makes with the normal is called the angle of reflection.

19. 1.] The incident ray, the reflected ray and normal at the point of incidence are always in thesame plane.

20. P O Q N M2M2M2M2 M1

21. 1.] The incident ray, the reflected ray and normal at the point of incidence are always in the same plane. 2.] 2.] The incident ray and reflected ray are always on opposite sides of the normal.

22. P O Q N M2M2M2M2 M1

23. 1.] The incident ray, the reflected ray and normal at the point of incidence are always in the same plane. 2.] The incident ray and reflected ray are always on opposite sites of the normal. 3.] 3.] The angle of the reflection is equal to the angle of incidence.

24. P O Q N M2M2M2M2 M1

25. POINTS TO REMEMBER SOURCES OF LIGHTSOURCES OF LIGHT NATURAL SOURCES ARTIFICIAL SOURCES EXTENDED SOURCES OF LIGHT POINT SOURCES OF LIGHT

26. SHADOWSSHADOWS UMBRA- A DARK SHADOW PENUMBRA- A LIGHT SHADOW POINTS TO REMEMBER

27. TERMS RELATED TO REFLECTIONTERMS RELATED TO REFLECTION INCIDENT RAY POINT OF INCIDENCE NORMAL REFLECTED RAY ANGLE OF INCIDENCE ANGLE OF REFLECTION POINTS TO REMEMBER