CBSE Class 12 Physics Refraction at Curved Surface Theory and Examples

Scroll down for PDF

CBSE Class 12 Physics Refraction at Curved Surface Theory and Examples. Please refer to the examination notes which you can use for preparing and revising for exams. These notes will help you to revise the concepts quickly and get good marks.

1. LAW OF REFRACTION AT SPHERICAL SURFACE
When light passes from a medium of refractive index μ1 to a medium of refractive index μ2 by a spherical surface of radius of curvature R then the relation between object distance u and image distance v is given by

class_12_physics_useful_0491

(1) All distances are measured from the pole (P).
(2) Distances measured in the direction of incident rays are taken as positive.
(3) Distances above the principal axis are taken as positive.
(4) Angles measured from the normal in the anticlockwise sense are positive.

DERIVATION
Suppose AB is the spherical surface which saparates the two medium of refractive index μ1 and μ2 .O and Ι is the position of object and image in medium of R.Ι. μ1 and μ2 repectively

class_12_physics_useful_0492

or ,
μ2/v– μ1/u = μ2 − μ1/ R
[For small aperture P & N are the same point]

1.2 Terms related to refraction at spherical surfaces

(A) centre of curvature (C) It is the centre of sphere of which the surface is a part.
(B) Radius of curvature (R) It is the radius of the sphere of which the surface is a part.
(C) Pole (P) It is the geometrical centre of the spherical refracting surface .
(D) Principal Axis It is the straight line joining the centre of curvature to the pole.
(E) Focus (F) When a narrow beam of rays of light, parallel to the principal axis and close to it (known as paraxial rays) is incident on a refracting spherical boundary , the refracted beam is found to converge or appear to diverge [depending upon the nature of the boundary (concave/canvex) and the refractive index of two media] from a point on the principal axis .This point is called focus.

Note :
(1) It is not always necessary that for convex boundary the parallel rays always converge. Similarly for concave boundary the incident parallel ray may converge or diverge depending upon the refractive index of two media,
(2) Laws of refraction are valid for spherical surface .
(3) Pole, centre of curvature, Radius of curvature, Principal axis etc. are defined as spherical mirror except for the focus.

class_12_physics_useful_0493

class_12_physics_useful_0494

Laws of refraction at curved surface

Ex.1 A small point object is placed at O, at a distance of 0.60 metre in air from a convex spherical surface of refractive index 1.5. If the radius of the curvature is 25 cm, then what is the position of the image on the principal axis ?

class_12_physics_useful_0495

Ex.2 The radius of a glass ball is 5 cm. There is an air bubble at 1cm from the centre of the ball, refractive index of glass is 1.5 then find
position of image (i) viewed from surface near the bubble, (ii) viewed from surface farther from the bubble.
Sol. (i) On viewing from the closer surface A (near to object) : The final image is formed at Ι.
 

class_12_physics_useful_0496

class_12_physics_useful_0497

Please click on below link to download pdf file for CBSE Class 12 Physics Refraction at Curved Surface Theory and Examples.


Click on the text For more study material for Physics please click here - Physics

Latest NCERT & CBSE News

Read the latest news and announcements from NCERT and CBSE below. Important updates relating to your studies which will help you to keep yourself updated with latest happenings in school level education. Keep yourself updated with all latest news and also read articles from teachers which will help you to improve your studies, increase motivation level and promote faster learning

CBSE Board Practical Exam 2020

CBSE Board Practical Exam 2020: Important changes in date sheet, internal/external examiners and more Are you doing preparations for class 10 and 12 CBSE board exams? If yes, then you have to see what major changes CBSE has brought in the CBSE date sheet for class 10...

CBSE will have more practicals

CBSE board has made a bigger announcement regarding 2020 board examinations for class 12. Board has decided that subjects like humanities, History, English and Hindi will also have practical exams like Chemistry, Biology, and Physics. As per, CBSE official's statement...

CBSE class 10, 12 board exam important information

CBSE class 10, 12 board exam: important information to prevent problems for students : The Central Board of Secondary Education (CBSE) has issued an advisory for the students of class 10 and class 12 board. As per the notice, the registration of students appearing in...

Sample Papers for Class 12 Boards 2020

CBSE has released the final sample papers for the class 12 boards exams as per the new pattern as per which the question papers are expected to come in the 2020 board exams for class 12. The sample papers have been for class 12 for all subjects along with the suggested...

Sample Papers for Class 10 Boards 2020

CBSE has recently released the Class 10 Sample Papers for Board exams which are to be held in March 2020. The sample papers have been for class 10 for all subjects along with the suggested marking scheme. CBSE releases these suggested papers every year so that the...

CBSE schools to have sports period daily for classes 1 to 12

CBSE schools to have sports period daily for classes 1 to 12, new curriculum introduced All work and no play makes a child dull. Nowadays students have a very hectic schedule so that they cannot take out time to play games and gently start ignoring sports. Therefore,...

×
Studies Today