GENERAL PHYSICS:OPTICS-IMAGE FORMATION.pptx

PRESENTATION

1. Image Formation

2. 2 Are the objects that you see actually real and concrete?

3. 3 In a body of water, the surface acts as a mirror and forms reflections of real objects.

4. 4 How does an image form?

5. 5 The way our eyes estimate distances of objects we see is based upon the assumption that a ray of light travels in a straight line. This assumption motivated the modeling of light as a ray . The study that treats light as a ray is called geometric optics . Image Formation

6. 6 The ray model of light explains that many light rays leave an object in many different directions, but only a few light rays can be traced to the person’s eye. Moving the person’s head at a different angle would allow another set of light rays to enter. Image Formation

7. 7 Image Formation by a Plane Mirror Image Formation A plane mirror is a mirror that has a flat and smooth surface. When you look at a plane mirror, you will see yourself and all the other objects in front of the plane mirror as an image.

8. 8 Image Formation by a Plane Mirror Image Formation The distance of the image formed by the plane mirror is equal to the distance of the object from the plane mirror.

9. 9 Image Formation by a Plane Mirror Image Formation The Law of Reflection states that the angle of reflection r is equal to the angle of incidence a . Suppose that a normal line from the plane mirror is at point B , the angle θ a must equal θ b .

10. 10 Image Formation by a Plane Mirror Image Formation Plane mirrors can only produce virtual images , or those formed when the light rays coming from a source do not intersect to form an image.

11. 11 Image Formation by a Plane Mirror Image Formation In contrast, a real image would have the light rays actually coming from the location of the image itself. For instance, if you place a paper on the position of the real image, the light rays will form an image of the object on the paper.

12. 12 Image Formation by a Spherical Mirror Image Formation Some mirrors that are curved are also useful in forming certain images. These mirrors are called spherical mirrors .

13. 13 Image Formation by a Spherical Mirror Image Formation A spherical mirror is convex if the light rays it reflects come out from the outer side of the spherical shape. For a concave mirror, the reflected rays come out from the inner side of the spherical shape.

14. 14 Image Formation by a Spherical Mirror Image Formation Spherical mirrors are either concave or convex.

15. 15 It is often helpful to think of the concave mirror as having the shape of a “cave” when you place the reflecting side facing the horizontal. In this manner, you can easily distinguish concave mirrors from convex mirrors!

16. 16 Image Formation by a Spherical Mirror Image Formation Spherical aberration is a defect that occurs when the outer parts of a mirror do not bring light rays into a similar focus as that of the central part.

17. 17 Image Formation by a Spherical Mirror Image Formation Parallel rays coming from the sun cannot converge on a single point and produce a sharp image. This is known as spherical aberration.

18. 18 Image Formation by a Spherical Mirror Image Formation Paraxial approximation may be applied to approximate the shape of the parabola by fitting a spherical shape on to it.

19. 19 Image Formation by a Spherical Mirror Image Formation The parallel rays striking a concave mirror can converge at the focus if paraxial approximation is applied.

20. A sharp image can be formed at a single point known as the focus , located at point F of the concave mirror. The line containing point A and point F is called the principal axis. 20 Image Formation

21. The distance between point A and point F is called the focal length . A real image of the Sun can now be seen at point F of the concave mirror. 21 Image Formation

22. 22 Image Formation The rays that meet at point F are called paraxial rays . Paraxial approximation takes advantage of the very small angles formed during reflection such that the length of line segment FB is approximately equal to the length of line segment FA.

23. 23 Image Formation by Refraction from a Surface Image Formation Light rays undergo refraction when they pass from one medium to another. Simply put, it is the bending of light rays. A surface that refracts light rays can also form images in a similar fashion on how a surface that reflects light can form an image.

24. 24 How do objects form images?

25. 25 Identify what is being referred to in each statement. This is a type of mirror where the reflected rays come out from the inner side of the spherical shape. The bending of light is called ________________. A ______________ image appears as if light rays are coming from the location of the image and not passing through it.

26. 26 Identify whether each of the following images formed is by a plane mirror, a spherical mirror, or a refractive surface.

27. 27 Identify whether each of the following images formed is by a plane mirror, a spherical mirror, or a refractive surface. 2.

28. 28 Identify whether each of the following images formed is by a plane mirror, a spherical mirror, or a refractive surface. 3.

29. 29 Identify what is being asked. This is a type of mirror where the reflected rays come out from the inner side of the spherical shape. The bending of light is called ________________. A ______________ image appears as if light rays are coming from the location of the image and not passing through it.

30. 30 A plane mirror can produce an image using the law of reflection . The image formed by a plane mirror is always a virtual image. The apparent distance of the image formed is equal to the object's distance from the plane mirror.

31. 31 A spherical mirror can either be concave or convex . A defect known as the spherical aberration affects the sharpness of the image formed by a concave mirror. A concave mirror can form a sharp image if paraxial approximation is applied.

32. 32 Paraxial approximation assumes that the reflection angle within the reflected rays is small enough such that the length of the reflected ray becomes approximately equal to the focal length. A concave mirror can form a real image at its focus. A convex mirror can only produce virtual images and cannot produce real images.

33. 33 A refracting surface can form an image using the law of refraction . The image formed by a refracting surface would appear to be bent to an observer.