Q:- 3 - Explain angular dispersion at single surface.
Q:- 4- What are defects or aberration of images?
Q:- 6- Write a note on prism binoculars..
Q:- 7 - State the law of refraction.
Answers
The answer to the above questions are;--
1)The phenomenon of splitting of white light into its component colours on passing through refracting medium is known as dispersion of light.When white light is passed through a prism it split into constituent colours, so the angular separation between the two extreme colours that is violet and red in the spectrum is called the angular dispersion.
2)Defects or aberration of images are;--
Defects in images formed by lenses are called as aberrations and are of two types they are:--(i)Monochromatic aberration:--
Also known as spherical aberration. The failure of paraxial and marginal rays to form a common image for object infront of lens or mirror on the principle axis is known as spherical aberration.
(ii)Chromatic aberration:--When a beam of white light passes through a lens and the failure of different colours of light to form a common image is called chromatic aberration and is caused due to variation of refractive index of lens with colour.
3)Prism binocular is a binocular with shortened telescopic tubes in each of which light rays entering through the objective lens are reflected by two Porro prisms before passing through eyepiece where finally an erect virtual image is formed . Used for bird watching and various purposes.
4)Laws of refraction are as follow:--
i)The incident ray, the refracted ray and the normal to the interface at the point of incidence all lie in same plane.
ii)The ratio of sin of angle of incidence to the sin of angle of refraction is constant for a given pair of media and is equal to refractive index of second medium with respect to first medium.
he second law is also known as Snell's law of refraction.