Reflection of light occurs according to following two laws called laws of reflection.
i. The incident ray, reflected ray and normal at the point of incidence, all lie in the same plane.
ii. The angle of incidence and the angle of reflection are equal. i.e.<i =<r
Defnie Angle of reflection:
Define angle of reflection: the angel between normal N and the reflected ray OB i.e. <NOB is called angle of reflection. r
What is meant by the term total internal reflection?
When a ray of light from denser medium enters a rare medium in such a way that angle of incident is greater then critical angle, then the ray is reflected totally inside and does not emerge out from the denser medium.This phenomenon is called total internal reflection.
Define Angle of incidence:
The angle between incident ray AO and normal N i.e. <AON is called angle of incidence.i
Define the refractive index in terms of speed of light.
The refractive index 'n' of a medium is the ratio of the speed of light 'c' in the vacuum to the speed of light 'v' in the medium.
What is the reflection of light?
When light travelling in a certain medium falls on a surface of another medium a part of it turns back in the same medium. It is called reflection of light.
Define angle of refraction:
The angle<r made by the refracted ray with the normal is called angle of refraction.
What is the Snell' law.
Snell's law: The ration sini/sinr is known as the refractive index of the second medium with respect to the first medium.
State the conditions for total internal reflection.
i. Lights rays should travel from denser medium to rare medium.
ii. Angle of incidence i. should be larger than critical angle.
State the laws of refraction.What is the Snell' law/
i. The incident ray, refracted ray and the normal at the point of incidence all lie in the same plane.
ii. The ratio of sine of angle of incidence to the sin of angle of refraction r is always equal to the constant
What is refraction of light?
the process of bending of light as it passes from air into glass and vice versa is called refraction of light.
Define Angle of incidence.
The angle <i made by the incident ray with the normal is called angle of incidence.
Difference between real and virtual images?
Ral image: i. It can be formed on screen.
ii. Rays of light actually meet at a point after refraction.
iii. Focal length of real image is taken positive.
What is meant by principal concave lens?
The light rays travelling parallel to the principal axis of a concave lens after refraction appear to come from a point behind the lens is called principal focus."F"
Define center of curvature:
A spherical mirror is a part of a sphere. The center of this sphere is called center of curvature.
What is meant by the principal focus of convex lens.
the light rays travelling parallel to the principal axis called principal focus or focal point. F.
Define Irregular reflection.
The reflection by the rough surface is called irregular reflection. e.g. reflection of paper or wall or rough surface.
What is critical angle?
When ray of light travel from denser medium to rare medium then the angle of incidence for which the angle of refraction becomes 90 degre is called critical angle.
Define regular reflection.
The reflection by the smooth surface is called regular reflection. e.g. Reflection of silver surface.
It is the midpoint of the curved surface of spherical mirror.It is also called vertex.
Define Radius of curvature:
It is the radius of the sphere of which spherical mirror is a part.
Compare the characteristics of image formed by concave mirrors and convex mirror.
Concave mirror: i. In concave mirror the size of the image depends on the position of the object.
ii. A convex mirror the size of the image is always smaller than the object.
Define power of lens. Give its mathematical form and SI unit.
It is defined as 'the reciprocal of focal length(f) of a lens when focal length is taken in meters.
POWERS OF LENS= P 1/D(m)
The SI unit of power of lens is dioptre denoted by D.
What do you mean by resolving power?
Resolving power of an instrument is its ability to distinguish between two closely placed objects or point sources.
The size of spherical mirror is called aperture.
Define focal length:
The distance from the pole to the principal focus, measured along the principal axis is called focal length.
What is the use of contact lens?
Contact lens show the same result as eyeglasses do .These are small thin lenses are placed directly on cornea a thin layer of tears between the lens and cornea keeps the lens in place.
Define principal focus.
After reflection from a concave mirror rays of light parallel to the principal axis converge to a point F. this point is called'The principle focus' of the mirror.
Define convex lens.
The lens which causes incident parallel rays to converge at a point is known as convex or converging lens.
Shape: This lens is thick at the centre but thin at the edges.
Define principal axis
It is the line joining center of curvature and pole of the spherical mirror.
How many types of lens.
There are two types of lens.
Give the uses of compound microscope;
It is used to study bacteria and other micro objects.
i. It is used to research in several fields of science like microbiology, biology, geology and genetics etc.
The study of light behaviour is called optics.
Define concave and diverging lens.
The lens which causes incident parallel rays of light to diverge from a point is called concave lens.
Shape: This lens is thin at the centre and the thick at the edges.
What is meant by angle of deviation?
When a ray is refracted through some refracted surface it deviates from its original path. The angle D made by the deviated ray with the normal is called angle of deviation.
What is lens? How it works ?
A lens is a transparent material having two surfaces of which at least one is curved.
Working lenses: Lenses refract light in such a way that an image of the object is formed.
What is pinhole camera?
Pinhole camera is simpler than a camera with one lens is a pinhole camera . To make a pinhole camera, a tiny pinhole is made in one side of a box. An inverted real image is formed on the opposite side of the box.
What is magnifying glass?
Magnifying glass is a lens that form s a virtual image that is larger than object and appears behind the lens.
Define Astronomical telescope.
i. Objective lens has larger focal length than the eyepiece.
ii. Distance between the objective lens and the eyepiece is equal to f0+fe.
iii. It is used to see distant astronomical objects.
What is Cystoscope.
The endoscope used to diagnose the bladder is called cystoscope.
What are geometrical optics.
The branch of optics that focuses on the creation of images is called geometrical optics, because it is based on relationship between angles and lines that describe light rays.
What is Gastroscopy.
the endoscope used to diagnose the stomach is called Gastroscope.
What is Bronchoscope.
The endoscope used to diagnose the throat is called bronchoscope.
What kind of nature light have?
Light has dual nature wave as well as particle nature.
What are the uses of endoscope?
An endoscope is used to explore the interior organs of body. Due to its small size it can be inserted through the mouth and thus eliminates the invasive surgery.