Reflection at plane surface

Law of Reflection
Field of View Formula
Total Deviation Formula
Multiple Images formed at 2 mirrors inclined
Two Parallel Mirrors. Reflection

1. REFLECTION AT A PLANE SURFACE CHAPTER 3

2. 3.1 IMAGES- VIRTUAL AND REAL a reflected light (diverging) at the surface and enters the eye as though it were coming from behind the surface. VIRTUAL IMAGE a reflected light is made to converge, an image is formed that actually exists. REAL IMAGE

3. 3.2 POSITION OF IMAGE FORMED BY PLANE MIRROR LAW OF REFLECTION be determined from 1. The angle of incident i is equal to the angle of reflection f. 2. T he incident ray, the rerflect ray and the normal at the same point of incidence, lie in the same plane. . governs the reflection of light-rays off smooth conducting surfaces, such as polished metal or metal-coated glass mirrors.

4. 3.3 FIELD OF VIEW OF A PLANE MIRROR FIELD OF VIEW is the extend of image in a plane mirror that can be seen by an eye in any position will depend on the size of the mirror and the position of the eye Q'R'=DE x OB'/OA=QR

5. 3.6 DEVIATION ON REFLECTION AT TWO MIRRORS IN SUCCESSION In this figure, the total deviation of the ray = ∠C₁ A₁ A₂ + ∠C₂ A₂ F = 2(∠EA₁ A₂ + ∠E A₂ A₁ ) =2 ∠ A₁ EH Therefore, total deviation = 2(180° -a) where a is the angle between the mirrors. Successive reflection from a two mirrors is used in all possible cases where considerable accuracy is required in the direction of a reflected beam. Providing the angle between the reflectors is accurately fixed, and this is frequently done by making them the surfaces of a prism, the correct placing of the mirrors with respect of the incident light need not be made with any great accuracy.

6. 3.7 MULTIPLE IMAGES FORMED ON REFLECTION AT TWO MIRRORS If an object is situated between two plane mirror more than two directs image will be formed, because some of light reflected at one mirror may be again reflected at the other mirror .

7. 3.8 TWO PARALLEL PLANE MIRRORS If an object B is placed between two plane mirrors, that are facing each other and parallel, the light will be reflected backwards and forwards between the mirrors giving rise to the images B’ ₁, B’ ₁. ₂ , etc. behind the mirror D ₁ E ₁ and the images B’ ₂, B’ ₂. ₁, etc. behind the mirror D ₂ E ₂, each image acting as an object for the mirror it is facing. It is clear that as the mirrors are parallel, the images and the object will be on a straight line and A ₁ B’ ₁ =BA ₁ A ₂ B’ ₂ =BA ₂ A ₁ B’ ₁. ₂ = B’ ₂ A ₁ A ₂ B’ ₂.₁ =B’ ₁ A ₂ A ₁ B’ ₁. ₂.₁ =B’ ₂.₁ A ₁ A ₂ B’ ₂ . ₁ . ₂ =B’ ₁ . ₂ A ₂ Theoretically, the number of images will be INFINITE, but as only a certain fraction of the incident light is reflected each time, each successive image is fainter than the preceding one, and the number of images seen will depend on the brightness of the original object.

8. 3.9 REFLECTION AS A MEANS OF ERECTING AN INVERTED IMAGES Reflection from a number of plane surface is often used as a means of erecting the inverted real image. the commonest application of this is in prism binocular.

9. 3.10 SEXTANT Another instrument that depends on the successive reflection at two mirrors. It is required to measure the angle between two distant object. Its used to measure the angle elevation of celestial body, usually sun or moon in order to determine one’s location and direction.