1.) Three Special rays for lenses.
2.) About Convex lens and where does the images form and about the above information.
3.) about Concave lens and its characteristics.
Answers
1.) QUESTION :-- Three Special Rays for lenses.
ANSWER :-- These rays help us to know the nature, size and position of the image formed when the object is kept at different distances from the lens. We generally used two of the three (special) incident rays, described below, to draw Ray diagrams :
- An incident ray, parallel to the principal axis, passes through (or appears to come from), the (second) principal focus of the lens.
- An incident ray, passing through the optical centre of the lens, goes undeviated from the lens.
- An incident ray, passing through the (first) principal focus of the lens, or directed towards it, becomes parallel to the principal Axis after refraction from the lens.
2.) QUESTION : What is convex lens ? and what are the characteristics of convex lens, where are the images formed ?
ANSWER : A convex lens from images of different size, nature, and at different positions, for objects kept at different distances from its optical centre. We consider the following 6 cases that cover all possible types of images formed by this lens. The characteristics, of the images formed have been written :
- Object at infinity : The image of a very far off object (object at infinity) is a real, diminished and almost point like image. It is formed at the focus of the lens.
- Object (somewhat) beyond the'2F' point of the lens : The image formed here is real, diminished ,inverted image. It is formed between the 'F' and '2F' points of the lens.
- Object at the '2F' point of the lens : The image formed here is a Real, inverted image that has the same size as the object. It is formed at the '2F' point of the lens, on the other side of the lens.
- Object between the '2F' and 'F' points of the lens : The image formed here is a real, inverted and magnified image. It is formed beyond the '2F' point of the lens, on its other side.
- Object kept at the (first) principal focus or the 'F' point of the lens : The image formed here is regarded as a real, inverted and magnified image. It is regarded as formed 'very far off', or at infinity.
3.) QUESTION : What is concave lens ? and its characteristics.
ANSWER : Unlike, a convex lens, the nature and position of the image formed by concave lens, does not depend upon the distance of the object from the lens. A concave lens always forms a virtual, erect and diminished image. Also, the image always appears to be located between the optic centre and 'F' point of the lens, on the same side as the object is. We illustrate these features of concave lens by drawing Ray diagrams for three different distances of the object from the lens.
In all the cases, the image formed is virtual, erect and diminished one. Also, it always appears to be formed between the optical centre and 'F' point of the lens.
The three special lenses of the lens say:
- X-ray radiation (Ray 1).
- Lane enters the lens at a line near the focus area (Rip 2).
- Radiation in the center of the lens (Ray 3).
About Convex lenses and where to create images and about the above information is:
- Convex Lens When an object is placed in an infinite position, the actual image is formed at the focus.
- Image size is much smaller than an object.
- When an object is placed behind a bend center, a real image is formed between the bending center and the focus.
About the Concave lens and its features are:
- Concave lenses have at least one curved area inside.
- A concave lens is also known as a peripheral lens because it has a circular shape in the center and protrudes out at the edges, making the light different.
- They are used to treat myopia as they make distant objects look smaller than they really are.