PROPERTIES OF LIGHT

PROPERTIES OF LIGHTLight like all waves can be reflected at a boundary between two media. This phenomena is simply called

REFLECTION

Light can also be transmitted from one medium to another. This phenomena is called

REFRACTION

REFLECTION OF LIGHT

SURFACE

NORMAL LINE

VIDEO

THIS VIDEO SHOWS HOW A BEAMS OF LIGHT ARE REFLECTED FROM A MIRROR

DIFFUSE AND SPECULAR REFLECTION

• MOST OBJECTS WILL PRODUCE BOTH SPECULAR AND DIFFUSE REFLECTION.

• THE RELATIVE AMOUNT OF EACH DEPENDS ON THE ANGLE FROM THE SURFACE THAT THE LIGHT IS OBSERVED.

VIDEO YOU CAN GET BOTH SPECULAR

AND DIFFUSE REFLECTION FROM A SURFACE.

GLARE

SPECULAR REFLECTION FROM A ROUGH SURFACE

OPTICAL DEVICES

OPTICAL DEVICES HAVE HAD A TREMENDOUS EFFECT ON THE EVOLUTION OF OUR CIVILIZATION.

IMAGES• OPTICAL INSTRUMENTS CAN BE USED TO

DIRECT THE LIGHT FROM AN OBJECT TO CREATE AN IMAGE.

• AN IMAGE IS A LOCATION IN SPACE THAT LOOKS EXACTLY LIKE THE OBJECT, BUT ITS SIZE AND ORIENTATION MAY BE DIFFERENT.

IMAGES• IF THE IMAGE IS LARGER THAN THE

OBJECT, IT IS SAID TO BE “MAGNIFIED”.

• IF THE OBJECT IS SMALLER THAN THE IMAGE, IT IS SAID TO BE “DIMINISHED”.

MIRRORS

LIGHT RAYS CAN BE DIRECTED VIA REFLECTION TO FORM IMAGES.

VIRTUAL IMAGES• VIRTUAL IMAGES ARE FORMED BY

MIRRORS THAT WE USE TO SEE OURSELVES.

• VIRTUAL IMAGES FORMED BY THESE MIRRORS ARE LOCATED ON THE OPOSITE SIDE OF THE MIRROR.

• SINCE NO LIGHT IS ACTUALLY AT THE IMAGE, THEY ARE CALLED VIRTUAL IMAGES.

VIDEO

• THESE VIDEO CLIPS SHOW THE IMAGES PRODUCED WHEN LIGHT IS REFLECTED FROM A PLANE , CONVEX AND CONCAVE MIRROR.

• ALL OF THESE IMAGES ARE VIRTUAL.

PLANE MIRROR

d d

objectvirtualimage

CONCAVE MIRROR

objectvirtualimage

CONVEX MIRROR

objectvirtualimage

REAL IMAGE

IF THE IMAGE IS ON THE SAME SIDE OF THE MIRROR AS THE OBJECT, IT IS SAID TO BE “REAL” SINCE THERE WILL BE LIGHT AT ITS LOCATION.

MIRROR SIMULATIONS

SURENDRANATH HAS SIMULATIONS ON HIS CD THAT SHOW HOW IMAGES ARE FORMED BY CONVEX AND CONCAVE MIRRORS.

REFRACTION

REFRACTIONThe change in the direction of travel due to a change in speed of the wave.

VIDEO

A PENCIL IN A GLASS OF WATER.

VIDEO

THE DIRECTION OF TRAVEL OF A TOY CAR IS AFFECTED AS IT TRAVELS ACROSS CARPET.

REFRACTIONThe angle of incidence or refraction is smaller in the medium in which the speed of light is slower.

This is usually a more dense medium.

REFRACTION SIMULATION

SURENDRANATH HAS SIMULATIONS ON HIS CD THAT SHOW HOW LIGHT WAVES ARE REFRACTED AS THEY TRAVEL FROM AIR INTO A DENSE MEDIUM. NOTICE THAT THE WAVES TRAVEL SLOWER IN THE MORE DENSE MATERIAL.

REFRACTION

MORE DENSE(SLOWER)

LESS DENSE(FASTER)

I

RF I

RF

LOCATING OBJECTS UNDER WATER

LENSES

VIDEO THIS VIDEO SHOWS HOW A LIGHT BEAM IS

REFRACTED THROUGH A LARGER ANGLE AS THE ANGLE OF THEN PRISM INCREASES.

CONVERGING LENS

FOCAL LENGTH

FOCAL POINT

DIVERGING LENS

focal length

Focal point

DEMONSTRATION

Hold a lens in front of your eye. Ask the kids if your eye looks larger or smaller.

Which type lens makes your eye look larger?

Which type lens makes your eye look smaller?

FAR SIGHTED• (HYPEROPIA)• DISTANT OBJECTS ARE SEEN

DISTINCTLY• THE EYE DOES NOT CONVERGE THE

LIGHT ENOUGH• A CONVERGENT LENS IS USED TO

CORRECT NEAR VISION

HYPEROPIA (far sighted)

HYPEROPIA CORRECTION

NEAR SIGHTED• (MYOPIA)• NEAR OBJECTS ARE SEEN DISTINCTLY• THE EYE CONVERGES THE LIGHT TOO

MUCH• A DIVERGENT LENS IS USED TO

CORRECT FAR VISION

MYOPIA (nearsighted)

MYOPIA CORRECTION

DISPERSIONTHE REFRACTION OF DIFFERENT WAVELENGTHS DUE TO THE FACT THAT THEY TRAVEL AT DIFFERENT SPEEDS THROUGH LIGHT MEDIA.

RAINBOW

SURENDRANATH HAS SIMULATIONS ON HIS CD THAT SHOW HOW LIGHT WAVES ARE REFRACTED BY RAINDROPS TO PRODUCE A RAINBOW.

DISPERSION CAUSES THE COLORS TO REFRACT AT DIFFERENT ANGLES.

PROPERTIES OF LIGHT SUMMARY

• REFLECTION– DIFFUSE & SPECULAR– IMAGES & MIRRORS

• REFRACTION– PRISMS AND LENSES– VISION CORRECTION– DISPERSION & RAINBOWS