REFLECTION AND REFRACTION

1

The Properties of Light

Linear Propagation

Refraction

Reflection

Diffraction

Polarization

2

The Characteristics of Images

TYPE

ORIENTATION

SIZE

3

TYPE OF IMAGE

Real vs VirtualReal Images can be seen on a piece of paper or screen placed because the focal point is in front of the mirror or behind the lens.

Virtual Images can not be seen on a piece of paper or screen, because the focal point is behind the mirror or in front of the lens. Virtual images are images which are formed in locations where light does not actually reach; it only appears to an observer as though the light were coming from this position.

4

ORIENTATION OF IMAGE

Inverted vs UprightInverted images are upside-down.

Upright images are right-side up.

5

SIZE OF IMAGE

Smaller, Larger, or Same SizeSmaller Images are reduced in size compared to the actual object.Larger Images are enlarged in size compared to the actual object.Same Size Objects are unchanged in size compared to the actual object.

Size is also discussed quantitatively in terms of Magnification.

6

Magnification (m)

The ratio of the size of the image to the size of the actual object.

The Magnification equation:

m = hm = hii/h/hoo = - d = - dii/d/doo

hhii is the height of the image, is the height of the image,

hhoo is the height of the object, is the height of the object,

ddoo is the distance of the object from the lens or is the distance of the object from the lens or

mirror, mirror,

ddii is the distance of the image from the lens or mirror. is the distance of the image from the lens or mirror.

7

Reflection

Light follows the same law of reflection as all other waves.

Both angles are measured from the normal to the surface at the point of incidence.

Glare- bright light that reflects to your eyes from the surface of smooth objects

8

Plane Mirrors

Plane mirrors are uniformly flat. The image is sent back virtual, erect, same size, and laterally inverted.

9

TYPES OF MIRROR

10

DEFINATIONS

Principal Axis: the straight line perpendicular to the surface of the mirror at its center.Focal Point: the location where the parallel rays of light from the source meet, or converge.Focal Length: the distance from the Focal Point to the mirror along the Principal Axis.Center of Curvature: twice the distance of the focal point to the mirror surface.

11

A Concave Mirror

12

Refraction

The change in direction or bending of light at the boundary between

two media.Refraction only occurs when the angle of

incidence is non-zero.

13

Practice Refraction

14

the index of refraction,n

A ray of light bends in such a way that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant.

This constant is called

Snell’s Law

15

Criteria for T.I.R.

1. Light must pass from a more optically dense to less optically dense medium.

2. There are only specific angles of incidence, called the critical angle, which is different for each medium.

To find the critical angle, use Snell’s Law, substituting 90º for r.

16

An Application of T.I.R.

Fiber optics.

Telephone, radio,video, and television signals can now be sent with light beams rather than electric currents.This is more energy-efficient. 

17

THANK YOU

18