Light
Light is a form of
energy, which aids our sense of sight. A body that emits light is called a
self-luminous body. The sun, the stars and the electric lamp are the best examples
of a self-luminous body. A body that does not emit light of its own is called a non-luminous body. Most of the objects are non-luminous bodies.
Light travels approximately
in straight lines in a given medium. This is known as rectilinear propagation
of light. Light travels with an enormous velocity of 186000 miles per second or
3 × 108 m/s.
Laws
of reflection
The incident ray, the
reflected ray and the normal to the reflecting surface at the point of
incidence all lie in the same plane.
The angle of incidence
is equal to the angle of reflection.
Reflection
of plane surface
When light travelling
in a medium falls on the surface of another medium, part of it is sent back
into the first medium itself. This phenomenon is known as reflection. The ray which
is sent back from the reflecting surface is called the reflected ray. The point
at which the ray is incident on the surface at the point of incidence is called
the normal.
Laws
of refraction
The incident ray, the
refracted ray and the normal at the point of incidence, all lie in the same
plane.
The ratio of the sine
of the angle of incidence to the sine of the angle of reflection is a constant
for the given two media.
Refraction
at plane surfaces
When a light ray passes from one medium to another, the
direction of the ray in the second medium is generally different from that in
the first medium. This bending of a ray is known as refraction light. When a ray passes from a denser to a rarer medium it bends away from the normal and when it passes from a rarer to denser medium it bends towards the normal.
Image
If rays of light
proceeding from a point, after reflection or refraction converge towards
another point, the second point is called the real image of the first point. If
the rays of light diverging from a point after reflection or refraction appear
to diverge from another point, the second point is called the virtual image of
the first.
Light - Laws of reflection - Laws of refraction - Image
Reviewed by knowledge people creators
on
January 27, 2019
Rating:
Reviewed by knowledge people creators
on
January 27, 2019
Rating:
