Refraction through lenses

Here is another creative presentation by your slide maker on the topic "Refraction through lenses". Hope you like it. If you like it then please *like*, *Download* and *Share*.

By- Slide_maker4u (Abhishek Sharma)
*******For presentation Orders, contact me on the Email addresses Written below********

Email- [email protected]
or
[email protected]
*******THANK YOU***************

1. Refraction through Lenses By Slide_maker4u ( Abhishek Sharma)

2. Introduction First lets consider a double convex lens. Suppose that several rays of light approach the lens; and suppose that these rays of light are traveling parallel to the principal axis. Upon reaching the front face of the lens, each ray of light will refract towards the normal to the surface. At this boundary, the light ray is passing from air into a more dense medium (usually plastic or glass). Since the light ray is passing from a medium in which it travels fast (less optically dense) into a medium in which it travels relatively slow (more optically dense), it will bend towards the normal line. This is the FST principle of refraction. This is shown for two incident rays on the diagram below. Once the light ray refracts across the boundary and enters the lens, it travels in a straight line until it reaches the back face of the lens. At this boundary, each ray of light will refract away from the normal to the surface. Since the light ray is passing from a medium in which it travels slow (more optically dense) to a medium in which it travels fast (less optically dense), it will bend away from the normal line; this is the SFA principle of refraction .

3. Refraction Rule for a Converging Lens Any incident ray traveling parallel to the principal axis of a converging lens will refract through the lens and travel through the focal point on the opposite side of the lens.   Now suppose that the rays of light are traveling through the focal point on the way to the lens. These rays of light will refract when they enter the lens and refract when they leave the lens. As the light rays enter into the more dense lens material, they refract towards the normal; and as they exit into the less dense air, they refract away from the normal. These specific rays will exit the lens traveling parallel to the principal axis.

4. Refraction Rules for a Converging Lens Any incident ray traveling parallel to the principal axis of a converging lens will refract through the lens and travel through the focal point on the opposite side of the lens. Any incident ray traveling through the focal point on the way to the lens will refract through the lens and travel parallel to the principal axis.

5. These two "rules" will greatly simplify the task of determining the image location for objects placed infront of converging lenses. This topic will be discussed in the next part of Lesson 5. For now, internalize the meaning of the rules and be prepared to use them. As the rules are applied in the construction of ray diagrams, do not forget the fact that Snells ' Law of refraction of light holds for each of these rays. It just so happens that geometrically, when Snell's Law is applied for rays that strike the lens in the manner described above, they will refract in close approximation with these two rules. The tendency of incident light rays to follow these rules is increased for lenses that are thin. For such thin lenses, the path of the light through the lens itself contributes very little to the overall change in the direction of the light rays. We will use this so-called thin-lens approximation in this unit. Furthermore, to simplify the construction of ray diagrams, we will avoid refracting each light ray twice - upon entering and emerging from the lens. Instead, we will continue the incident ray to the vertical axis of the lens and refract the light at that point. For thin lenses, this simplification will produce the same result as if we were refracting the light twice. The Thin Lens Approximation

6. Refraction Rule for a Diverging Lens Any incident ray traveling parallel to the principal axis of a diverging lens will refract through the lens and travel  in line with  the focal point (i.e., in a direction such that its extension will pass through the focal point).  Now suppose that the rays of light are traveling towards the focal point on the way to the lens. Because of the negative focal length for double concave lenses, the light rays will head towards the focal point on the opposite side of the lens. These rays will actually reach the lens before they reach the focal point. These rays of light will refract when they enter the lens and refract when they leave the lens. As the light rays enter into the more dense lens material, they refract towards the normal; and as they exit into the less dense air, they refract away from the normal. These specific rays will exit the lens traveling parallel to the principal axis.

7. Any incident ray traveling parallel to the principal axis of a diverging lens will refract through the lens and travel  in line with  the focal point (i.e., in a direction such that its extension will pass through the focal point). Any incident ray traveling towards the focal point on the way to the lens will refract through the lens and travel parallel to the principal axis. Refraction Rules for a Diverging Lens

8. A Third Rule of Refraction for Lenses The above discussion focuses on the manner in which converging and diverging lenses refract incident rays that are traveling parallel to the principal axis or are traveling through (or towards) the focal point. But these are not the only two possible incident rays. There are a multitude of incident rays that strike the lens and refract in a variety of ways. Yet, there are three specific rays that behave in a very predictable manner. The third ray that we will investigate is the ray that passes through the precise center of the lens - through the point where the principal axis and the vertical axis intersect. This ray will refract as it enters and refract as it exits the lens, but the net effect of this dual refraction is that the path of the light ray is not changed. For a  thin lens , the refracted ray is traveling in the same direction as the incident ray and is approximately in line with it. The behavior of this third incident ray is depicted in the diagram below. .

9. Refraction Rules for a Converging Lens Any incident ray traveling parallel to the principal axis of a converging lens will refract through the lens and travel through the focal point on the opposite side of the lens. Any incident ray traveling through the focal point on the way to the lens will refract through the lens and travel parallel to the principal axis. An incident ray that passes through the center of the lens will in effect continue in the same direction that it had when it entered the lens.

10. Refraction Rules for a Diverging Lens Any incident ray traveling parallel to the principal axis of a diverging lens will refract through the lens and travel  in line with  the focal point (i.e., in a direction such that its extension will pass through the focal point). Any incident ray traveling towards the focal point on the way to the lens will refract through the lens and travel parallel to the principal axis. An incident ray that passes through the center of the lens will in effect continue in the same direction that it had when it entered the lens.

11. Here is another creative presentation by your slide maker on the topic “REFRACTION THROUGH LENSES ". Hope you like it. If you like it then please *like*, *Download* and *Share*. By- Slide_maker4u ( Abhishek Sharma) *******For presentation Orders, contact me on the Email addresses Written below******** Email- [email protected] or [email protected] *******THANK YOU***************