1. Propagation & Reflection Of Light
Chapter 13
Propagation & Reflection Of Light

2. REFLECTION OF LIGHT
When light rays traveling is a medium reaches the boundary of other medium, they turn back to the     first medium. This phenomenon of turning back of light into the same medium after striking the boundary     of other medium is called Reflection of Light

3. LAWS OF REFLECTION
    1. The angle of incident is equal to the angle of reflection i.e. <i = <r     2. The incident ray, the reflected ray and the normal lie on the same plane.

4. REGULAR REFLECTION
When a beam pass of parallel light rays is incident on a smooth and plane surface, the reflected rays will     also be parallel. This type of reflection is called Regular Reflection.

5. IRREGULAR REFLECTION
When a beam of parallel light rays is scattered in all directions. Therefore the parallel rays incident on     the surface will reflect in different directions. This type of reflection is called "Irregular or Diffuse     Reflection".

6. CENTER OF CURVATURE
Center of curvature of a lens or mirror is defined as the center of the sphere of which the less or mirror     is a part. C = Center of curvature.

7. RADIUS OF CURVATURE
    Radius of curvature is the radius of sphere of which the lens or mirror is a part. 
PC = Radius of curvature OR PC = R

8. POLE
   The middle or center point of a lens or a mirror is called "Pole" P = Pole. 
PRINCIPLE AXIS
    The straight line joining the center of curvature to the pole is called Principle Axis. .

9. PRINCIPLE FOCUS
When a narrow beam of light, parallel to the principle axis and closed to it, is incident on the surface of     a mirror or lens, the beam reflected or refracted is converged at a fixed point on the axis. This point is     called Principle Axis.      F = principle focus.

10. FOCAL LENGTH
    The distance between the pole of a lens or mirror to the principal focus is called Focal Length (PF) of     lens or mirror. Focal length is always equal to half of the radius of curvature of lens or mirror. f = R/2. 
    Write down the characteristics of image formed by a plane mirror   
Image formed by plane mirror is laterally inverted. This means that right side of the object appears on     the left side.
    2. Size of image formed by plane mirror is the same as that of size of object.      3. The image formed by plane mirror is virtual because it can not be obtained on the
screen.     4. The image is as far behind the mirror as the object is in front of the mirror. Fig.

11. SPHERICAL MIRROR AND IT'S TWO TYPES
    Mirror obtained from a spherical surface is known as Spherical Mirror. A spherical mirror is considered as     a section of hollow sphere.
TYPES OF SPHERICAL MIRRORS
    There are two types of spherical mirrors.      1. Concave mirror.      2. Convex mirror.
CONCAVE MIRROR
    If the inner side of the surface of a spherical mirror is polished to reflect light, the mirror is called a     Concave Mirror. Concave mirror converges parallel beam of light.
CONVEX MIRROR
    If the outer side of the surface of a spherical mirror is polished to reflect light the mirror is called a     Convex Mirror. Convex mirror diverges parallel beam light.

12. MAGNIFICATION
    Magnification of a mirror or lens is defined as the ratio of the size of image to the size of object.
M = height of image/height of object M = hi/ho  or M = q/P

13. REFRACTIVE INDEX 
    Refractive index is defined as the ratio of sine of the angle of incidence of the sine of the angle of     refraction. FORMULA :
mew= sine< i/ sine< r
    note :Refractive index depends upon the nature of material.      It has no unit.
ANGLE OF DEVIATION 
    The angle at which the light ray is refracted (bend) in a prism is called angle of deviation. It is denoted     by < D. Minimum value of angle of deviation is called angle of minimum deviation. It is denoted by      <Dm.

14. Image Formation by convex lens
POSITION OF OBJECT When the object is placed at infinity 
NATURE AND POSITION OF IMAGE 1. The image will form at the principal focus (F).  2. The image will be real and inverted. 3. The image will be very small in size.

15. POSITION OF OBJECT When the object is placed beyond 2F
NATURE AND POSITION OF IMAGE 1. The image will form between F and 2F.  2. The image will be real and inverted. 3. The image will be smaller in size.

16. POSITION OF OBJECT When the object is placed at 2F
NATURE AND POSITION OF IMAGE 1. The image will form at 2F.  2. The image will be real and inverted. 3. The image will be equal in the size of object

17. POSITION OF OBJECT When the object is placed between F and 2F
NATURE AND POSITION OF IMAGE 1. The image will form beyond 2F.  2. The image will be real and inverted. 3. The image will be magnified.

18. POSITION OF OBJECT When the object is placed
NATURE AND POSITION OF IMAGE 1. The image will form at infinity.  2. The image will be real and inverted. 3. The image will be highly magnified.

19. POSITION OF OBJECT When the object is placed between the pole (P) and F 
NATURE AND POSITION OF IMAGE 1. The image will form on the same side of object.  2. The image will be virtual and erect. 3. The image will be magnified.