Q. 114.4( 21 Votes )

State the laws of

Answer :

The laws of refraction, also known as Snell’s law of refraction describes the behaviour of light as it goes across an interface from a one medium to another.


The following two statements are the laws of refraction of light:


(i) The incident ray, refracted ray and the normal to the interface of the two separate media at the point of incidence, all lies in the same plane.


(ii) The ratio of the sine of angle of incidence to the sine of angle of incidence for a given pair of media and the colour of light is always constant.


If i and r are the angles made by the incident ray and the refracted ray, respectively, at the point of incidence, then we can write;



The term absolute refractive index is defined as the ratio of the speed of light in the vacuum to the speed of light in a certain medium. It can also be expressed as,


nm =


OR


The ability of a lens to converge or diverge the light rays, depending on the nature of the lens is measured in terms of the power of the lens. It is defined as the inverse of focal length, described as;



The SI unit of power of a lens is called Dioptre. It is often denoted by letter D. Since, the focal length of a lens is expressed in meters, then, power is expressed in Dioptre. Thus, the power of a lens of a focal length of 1m is 1D, and its unit is m-1.


The question has given two lenses with focal length values as following;


Let’s call it f1 and f2.


f1 = 40 cm


f2 = -20cm


Now, the corresponding values of power of these lenses are, say P1 and P2.


Power of a lens is defined as,



Therefore, for the lens 1,


P1 = =


The value of power in this case is positive in nature that signifies that the lens is converging in nature.


Similarly, for the lens 2,


P1 = =


The power of this lens is negative, that speaks about the nature of the lens. A lens with a negative power is diverging in nature In conclusion, a lens with negative power is always diverging in nature and for positive power the converging capacity of the lens is significant.


Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Glimpses of IndiaGlimpses of IndiaGlimpses of India39 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
caricature
view all courses
RELATED QUESTIONS :

A convex lens of All In One Science

State and define All In One Science

Two lenses have pAll In One Science

When two or more All In One Science

State the laws ofScience - Board Papers

The image of an oXam idea - Science

A concave lens haXam idea - Science

The optical prescLakhmir Singh & Manjit Kaur - Physics

What is the powerScience Lab Manual