Reflection of light class 10 | 10th class physics | punjab, federal, kpk, balochistan board

Reflection of light in urdu or reflection of light 10th physics chapter 11 reflection of light physics wallah sabaq.
12.1 REFLECTION OF LIGHT
Reflection of light is illustrated in Fig. 12.1. When a ray of light
from air along the path AO falls on a plane mirror M, it
Types of Reflection
Nature of reflection depends on smoothness of the surface.
For example, a smooth surface of silver reflects rays of light in
one direction only. The reflection by these smooth surfaces is
called regular reflection (Fig.12.2). Most of the objects in
everyday world are not smooth on the microscopic level. The
rough surfaces of these objects reflect the rays of light in
many directions. Such type of reflection is calle

SUMMARY
 When light travelling in a certain medium falls on the surface of another
medium, a part of it turns back in the same medium. This is called reflection of
light. There are two laws of reflection:
i. The incident ray, the reflected ray, and the normal all lie in the same plane.
ii. The angle of incidence is equal to the angle of reflection (i.e., i = r).
 Like plane surfaces, spherical surfaces also reflect light satisfying the two
laws of reflection.
 In mirrors, image formation takes place through reflection of light while in
lenses image is formed through refraction of light.
 The equation relating the distance of the object p from the mirror/lens,
distance of the image q and the focal length f of the mirror/lens is called
mirror/lens formula, given by
 Magnification of a spherical mirror or thin lens is defined as “the ratio of the
image height to the object height.” i.e.,
 Power of a lens is defined as “the reciprocal of its focal length in metres”. Thus Power
of a lens = P = 1 / focal length in metres. The SI unit of power of a lens is “Dioptre”,
-1 denoted by a symbol D. If is expressed in metres so that 1 D = 1 m . Thus, 1 Dioptre f
is the power of a lens whose focal length is 1 metre.
 The refractive index ‘n’ of a material is the ratio of the speed of light ‘c’ in air to the
speed of light ‘v’ in the material, thus
 The bending of light from its straight path as it passes from one medium into another
is called refraction.
 Refraction of light takes place under two laws called laws of refraction. These are
stated as:
i. The incident ray, the refracted ray, and the normal at the poin
always equal to a constant i.e., = constant.
where the ratio is equal to the refractive index of the second medium with
respect to the first medium.
i.e.,
This is also called Snell's law.
.

o
The angle of incidence for which the angle of refraction becomes 90 is called critical
angle. When the angle of incidence becomes larger than the critical angle, no
refraction occurs. The entire light is reflected back into the denser medium. This is
known as total internal reflection of light.
 A simple microscope, also known as a magnifying glass, is a convex lens which is
used to produce magnified images of small objects.
 A compound microscope is used to investigate structure of small objects and has
two converging lens, the objective and the eyepiece.
 Telescope is an optical instrument which is used to observe distant objects using
lenses or mirrors. A telescope that uses two converging lenses is called refracting
telescope. A telescope in which the objective lens is replaced by a concave mirror is
called reflecting power telescope.
 The magnifying power is defined as “the ratio of the angle subtended by the image as
seen through the optical device to that subtended by the object at the unaided eye”.
 The resolving power of an instrument is its ability to distinguish between two closely
placed objects.
 The ability of the eye to change the focal length of its lens so as to form a clear image
of an object on its retina is called its power of accommodation.
 The disability of the eye to form distinct images of distant objects on its retina is
known as nearsightedness. The nearsighted eye can be corrected with glass or
contact lenses that use diverging lenses Light rays from the distant objects will .
diverge by this lens before entering the eye.
 The disability of the eye to form distinct images of nearby objects on its retina is
known as farsightedness. This defects can be corrected with the aid of a suitable
converging lens. The lens refracts the light rays more toward

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[spnx.fx_]

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[atgmcareerandgoals]

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[ghazalashaheen]

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[shagufta]

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[nazirhassan]

Sir irregular reflection mn reflection ky laws follow hoty hn kia?