Terms for Lenses
Terms for Lenses
The lenses are made of two curved surfaces which are a part of the sphere. The diagram below shows important terms related to Convex Lens.
The diagram below shows important terms related to Concave Lens.
Optical Centre (O):
The central point O of the lens is called its optical centre. A ray incident towards the optical centre passes almost without any deviation through the lens.
Centres of Curvature:
The centres of the two imaginary spheres of which the lens is a part are called centre of curvature of the lens. It represented by . A lens has two centres of curvature with respect to its two curved surfaces.
Radii of Curvature:
The radii of the two imaginary spheres of which the lens is a part are called radii of curvature of the lens. A lens has two radii of curvature. These may or may not be equal.
Principal Axis:
Lens is bounded by two spherical surfaces, and therefore, has two centres of curvature and
. The imaginary line joining them is called the Principal Axis of the lens.It passes through the optical centre.
Principal Focus
A lens has two surfaces and hence two focal points first focal point is an object on the principal axis foe which image is at infinity while second focal point is an image point on the principal axis for which object is at infinity.
First Principal Focus It is a point on the principal axis of lens, the rays starting from or directed to which become parallel to principal axis after refraction.
Second Principal Focus It is the point on the principal axis at which the rays coming parallel to the principal axis converge on the other side of lens (convex) or appear to meet on the same side of lens (concave) after refraction from the lens.
Both the foci of convex lens are real while that of concave lens are virtual.
Focal Length:
The distance between optical centre of a lens and the point where the parallel beam of light converge or appear to diverge from i.e. focus is called focal length.
Focal Plane:
The plane passing through the focus and perpendicular to the principal axis is called focal plane.
Aperture :
The effective diameter of its light transmitting area is called the aperture of lens. It controls the brightness i.e. intensity of image formed by a lens which depends on the light passing through the lens. It is proportional to the square of aperture.i.e.
For a lens there is/are _____________ centres of curvature. | |||
| Right Option : B | |||
| View Explanation | |||
Which of the following are correct ? (a) The lenses are made of two curved surfaces which are a part of the sphere. (b) Lens is bounded by two spherical surfaces, and therefore, has two centres of curvature (c) The effective diameter of its light transmitting area is called the aperture of lens. | |||
| Right Option : D | |||
| View Explanation | |||
The central point of the lens is called its ____________________ and a ray incident towards this point passes almost without any deviation through the lens. | |||
| Right Option : A | |||
| View Explanation | |||
Students / Parents Reviews [20]
A marvelous experience with Abhyas. I am glad to share that my ward has achieved more than enough at the Ambala ABHYAS centre. Years have passed on and more and more he has gained. May the centre flourish and develop day by day by the grace of God.
Archit Segal
7thAbhyas Methodology is very good. It is based on according to student and each child manages accordingly to its properly. Methodology has improved the abilities of students to shine them in future.
Manish Kumar
10thIt was good as the experience because as we had come here we had been improved in a such envirnment created here.Extra is taught which is beneficial for future.
Eshan Arora
8thAbhyas institute is one of the best coaching institute in the vicinity of Ambala cantt.The institute provides good and quality education to the students.The teachers are well experienced and are very helpful in solving the problems. The major advantages of the institute is extra classes for weak...
Shreya Shrivastava
8thAbhyas institute is one of the best coaching institute in the vicinity of Ambala Cantt area. The teachers of the institute are well experienced and very helpful in solving the problems of the students.The good thing of the institute is that it is providing extra classes for the students who are w...
Aman Kumar Shrivastava
10thWe started with lot of hope that Abhyas will help in better understnding of complex topics of highers classes. we are not disappointed with the progress our child has made after attending Abhyas. Though need to mention that we expected a lot more. On a scale of 1-10, we would give may be 7.
Manya
8thWhen I have not joined Abhyas Academy, my skills of solving maths problems were not clear. But, after joining it, my skills have been developed and my concepts of science and SST are very well. I also came to know about other subjects such as vedic maths and reasoning.
Sharandeep Singh
7thAbhyas is good institution and a innovative institute also. It is a good platform of beginners.Due to Abhyas,he has got knoweledge about reasoning and confidence.My son has improved his vocabulary because of Abhyas.Teacher have very friendly atmosphere also.
Manish Kumar
10thOne of the best institutes to develope a child interest in studies.Provides SST and English knowledge also unlike other institutes. Teachers are co operative and friendly online tests andPPT develope practical knowledge also.
Aman Kumar Shrivastava
10thMy experience with Abhyas Academy has been very good. When I was not in Abhyas whenever teacher ask questions I could not speak it confidently but when I came in Abhyas, my speaking skills developed and now I am the first one to give the answer of teachers question.
Upmanyu Sharma
7thAbhyas is an institute of high repute. Yogansh has taken admission last year. It creates abilities in child to prepare for competitive exams. Students are motivated by living prizes on basis of performance in Abhyas exams. He is satisfied with institute.
Yogansh Nyasi
7thAbhyas is a complete education Institute. Here extreme care is taken by teacher with the help of regular exam. Extra classes also conducted by the institute, if the student is weak.
Om Umang
10thMy experience with Abhyas academy is very good. I did not think that my every subject coming here will be so strong. The main thing is that the online tests had made me learn here more things.
Hiya Gupta
8thUsually we see institutes offering objective based learning which usually causes a lag behind in subjective examinations which is the pattern followed by schools. I think it is really a work of planning to make us students grab the advantages of modes of examination, Objective Subjective and Onli...
Anika Saxena
8thThe experience was nice. I studied here for three years and saw a tremendous change in myself. I started liking subjects like English and SST which earlier I ran from. Extra knowledge gave me confidence to overcome competitive exams. One of the best institutes for secondary education.
Aman Kumar Shrivastava
10thAbhyas academy is great place to learn. I have learnt a lot here they have finished my fear of not answering.It has created a habit of self studying in me.The teachers here are very supportive and helpful. Earlier my maths and science was good but now it has been much better than before.
Barkha Arora
10thMy experience with Abhyas academy is very nice or it can be said wonderful. I have been studying here from seven class. I have been completing my journey of three years. I am tinking that I should join Abhyas Academy in tenth class as I am seeing much improvement in Maths and English
Hridey Preet
9thThird consective year,my ward is in Abhyas with nice experience of admin and transport support.Educational standard of the institute recumbent at satisfactory level. One thing would live to bring in notice that last year study books was distributed after half of the session was over,though study ...
Ayan Ghosh
8thIn terms of methodology I want to say that institute provides expert guidence and results oriented monitering supplements by requsite study material along with regular tests which help the students to improve their education skills.The techniques of providing education helps the students to asses...
Aman Kumar Shrivastava
10thI have spent a wonderful time in Abhyas academy. It has made my reasoning more apt, English more stronger and Maths an interesting subject for me. It has given me a habbit of self studying
