DEFINITIONS
 
.
 
REFLECTION OF LIGHT
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    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.
LAWS OF REFLECTION
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    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.
 
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.
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".
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.
RADIUS OF CURVATURE
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    Radius of curvature is the radius of sphere of which the lens or mirror is a part.
PC = Radius of curvature
OR
PC = R
POLE
 
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    The middle or center point of a lens or a mirror is called "Pole" P = Pole.
PRINCIPLE AXIS
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    The straight line joining the center of curvature to the pole is called Principle Axis. .
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.
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
    1. 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.
DEFINE SPHERICAL MIRROR
AND IT'S TWO TYPES
 
SPHERICAL MIRROR
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    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.
MAGNIFICATION
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    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
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 :
m= 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.
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