REFLECTION OF LIGHT DEFINITIONS

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.
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.
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
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
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
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
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.

THERMAL CONDUCTIVITY

THERMAL CONDUCTIVITY
Thermal conductivity is defined as" the amount of heat conducted in one second through one cubic meter of a substance whose two opposite faces are maintained at the temperature difference of one degree centigrade." It is denoted by "K". Formula K=QL/ADTt Unit : Unit of thermal conductivity is J/mKs OR watt/m.K.
EXPRESSION FOR THERMAL CONDUCTIVITY
Experiments indicates that the amount of heat conducted through a solid block is :  Directly proportional to temperature difference between two faces of block.
DQ a DT ...................... (i)
Directly proportional to the area of cross - section of block.
DQ a A ...................... (ii)
Directly proportional to the the time interval to which heat is conducted.
DQ a t ...................... (iii)
Inversly proportional to the length of block.
DQ a 1/L ...................... (iv)
Combining above facts,we get
DQ a DT.A.t /L
OR
OR

DISTRIBUTIVE LAW FOR DOT PRODUCT

DISTRIBUTIVE LAW FOR DOT PRODUCT
According to distributive law for dot product:
	PROOF
	Consider three vectors , and .Here we will use geometric interpretation of dot product by drawing projection as shown below. First we obtain the sum of vectors  and by head to tail rule then we draw projection  and from the terminal point of vector respectively onto the direction of . The dot product  is equal to the projection of vector  onto the direction of  multiplied by the magnitude of. i.e.

AREA OF PARALLELOGRAM

COMMUTATIVE LAW OF VECTOR ADDITION
Consider two vectors and  . Let these two vectors represent two adjacent sides of a parallelogram. We construct a parallelogram
OACB as shown in the diagram. The diagonal OC represents the resultant vector
	From above figure it is clear that:
	This fact is referred to as the commutative law of vectr addition .
	ASSOCIATIVE LAW OF VECTOR ADDITION
	The law states that the sum of vectors remains same irrespective of their order or grouping in which they are arranged. Consider three vectors ,  and
	Applying "head to tail rule" to obtain the resultant of (+ ) and (+ )
	Then finally again find the resultant of these three vectors :
	This fact is known as the ASSOCIATIVE LAW OF VECTOR ADDITION.