Shirin Shahana.N Academis

1. LIGHT-REFLECTION &
REFRACTION(CBSE)
Shirin Shahana.N
Academis

2. REFLECTION OF LIGHT
• When a ray of light approaches a smooth polished surface and the
light ray bounces back , it is called the reflection of light.
•LAWS OF REFLECTION
1. The angle of incidence is equal to the angle of reflection.
2. The incident ray , the reflected ray and the normal to the mirror alie
in the same plane.

3. SPHERICAL MIRRORS
• Concave Mirror : A spherical mirror that has its reflecting surface
curved inwards.
• Convex Mirror : A spherical mirror that has its reflecting surface curved
outwards
• Plane mirror : A plane mirror is a mirror with a flat reflective surface.

4. TERMS RELATED TO MIRRORS
1. Center of curvature ( C ) : It is the center of the
sphere of which the mirror is a part.
2. Radius of curvature ( CP ) : It is the radius of
the sphere of which the mirror is a part.
3. Pole ( P ) : It is the center of the spherical
mirror.
4. Principal axis : It is the straight line passing
through the center of curvature and the pole.
5. Principal Focus(F)
• Concave Mirror : It is a point on the principal
axis , where all the rays parallel the principal
axis converge.

5. • Convex Mirrors :It is a point on the principal principal axis,where the
reflected rays appear to converge.
5. Focal length(f) : The distance between the pole and the principal
focus is called the focal length of the spherical mirror
• The Radius of Curvature is two times the Focal Length of any
spherical mirror.

7. RULES FOR REFLECTION OF LIGHT THROUGH
SPHERICAL MIRRORS
1. Ray parallel to principal axis
will pass through focus after
reflection.
2. A ray passing through the
focus of a concave mirror
after reflection will emerge
parallel to the principal axis.

8. 3. A ray passing through the center of
curvature after reflection is reflected back
along the same path.
4. A ray incident obliquely to the principal axis
towards the pole on the spherical mirrors is
reflected back obliquely.

9. IMAGE FORMATION BY CONCAVE MIRRORS
1.Object at F
Real & inverted
At infinity
Highly magnified
2. Between F & P
Virtual & erect
Behind the mirror
Magnified
3.At infinity
Real & inverted
Highly diminished,point sized
Formed at F

10. 4. Beyond C
Real & inverted
Between F & C
Diminished
5. At C
Real and Inverted.
At C
Same size as the object
6. Between F and C
Real and Inverted
Beyond C
Magnified

12. IMAGE FORMATION BY CONVEX MIRROR
1. At Infinity
Virtual and Erect
Behind the mirror ( at F )
Highly diminished
2.Between Infinity and P
Virtual and Erect
Behind mirror(between P & F)
Diminished

13. USES OF CONCAVE MIRRORS
1. Shaving mirrors.
2. Torches , search lights and vehicle headlights.
3. Used by dentist to get large images of patient's teeth.
4. In solar furnaces to concentrate heat.
USES OF CONVEX MIRRORS
1. Vehicles as rear - view mirrors to see traffic at the rear – side.
2. Used as a device to check thefts in shops

14. NEW CARTESIAN SIGN CONVENTIONS
• Object is placed left to
the mirror and the pole is
taken as the origin.
• Distance to the right of
origin ( +ve X - axis ) is
positive while that to its
left ( -ve X - axis ) is
negative.
• Distances above the
principal axis ( + ve Y -
axis ) are positive while
those below it ( -ve Y -
axis ) are negative.

20. TERMS RELATED TO LENSES
• The center point of a lens is known as its Optical centre.
• A line passing through the optical center is the Principal Axis.
• Focus is the point where rays converge (or appear to ) after refraction
in lens.

21. RULES FOR DRAWING RAY DIAGRAMS
• 1. A ray of light parallel to
the principal axis passes
through the focus after
refraction.
• 2. A ray of light passing
through the focus
becomes parallel to the
principal axis after
refraction.
• 3. A ray of light passing
through the optical
centre goes straight
without changing its
path.

28. DIFFERENCE BETWEEN LENSES AND MIRRORS