LIGHT AND ITS USES
Jan 11, 2016
LIGHT AND ITS USES
LIGHT RAY
STRAIGHT LINE
PATH OF LIGHT
RAY MODEL OF LIGHT
• THE RAY MODEL OF LIGHT ASSUMES LIGHT
RAYS SPREAD OUT IN ALL DIRECTIONS IN
STRAIGHT-LINE PATHS CALLED LIGHT RAYS.
• AN IMAGE IS FORMED WHEN THE LIGHT
RAYS LEAVING THE OBJECT FROM THE SAME
POINT MEET.
SHADOWS
• SHADOWS OCCUR BECAUSE LIGHT
TRAVELS IN STRAIGHT LINES
• IF AN OBJECT GETS INTO THAT BEAM,
THE OBJECT BLOCKS SOME OF THE
LIGHT & A SHADOW IS CREATED.
REFLECTION OF LIGHT
WHEN LIGHT STRIKES A SURFACE,
SOME OF THE LIGHT BOUNCES BACK
(IS REFLECTED). THE REST IS EITHER
ABSORBED BY THE MATERIAL OR
TRANSMITTED THROUGH IT.
REFLECTION OF LIGHT
LAW OF REFLECTION
• LIGHT WILL BE REFLECTED
OFF A SURFACE AT THE SAME
ANGLE AS IT STRIKES THE
SURFACE.
THE TYPE OF SURFACE THE LIGHT STRIKES
DETERMINES THE KIND OF REFLECTION
SURFACE TEXTURE
SMOOTH SURFACE = RAYS HIT AT
THE SAME ANGLE, THUS ARE
REFLECTED AT THE SAME ANGLE.
THIS IS CALLED
REGULAR REFLECTION
WHEN THE SURFACE IS NOT SMOOTH, OR
IRREGULAR, EACH LIGHT RAY HITS THE
SURFACE AT A DIFFERENT ANGLE.
THIS IS CALLED
DIFFUSE REFLECTION
IT STILL OBEYS THE LAW OF REFLECTION,
SO EACH RAY IS REFLECTED AT A
DIFFERENT ANGLE FROM THE OTHERS.
THE REFLECTED RAYS ARE SCATTERED IN
ALL DIRECTIONS
DIFFUSE
REFLECTION
MIRRORS
PLANE MIRROR
• MIRROR WITH A VERY, VERY, VERY, VERY, VERY FLAT
SURFACE• EX: WALL OR POCKET MIRROR
CHARACTERISTICS OF PLANE MIRRORS
• THE IMAGE IS RIGHT SIDE UP
• THE IMAGE IS THE SAME SIZE AS THE
ORGINAL OBJECT
• LEFT & RIGHT ARE REVERSED
• THE IMAGE APPEARS TO BE ON THE OTHER SIDE
OF THE MIRROR = VIRTUAL IMAGE (NOT REAL)
VIRTUAL IMAGE
• THE LIGHT RAYS REFLECTED DON’T
ACTUALLY MEET, BUT THE IMAGE SEEMS
TO BE LOCATED WHERE THE LIGHT RAYS
WOULD MEET
• MEANS NOT REAL; THE IMAGE CAN ONLY
BE SEEN IN THE MIRROR
CONCAVE MIRRORS
• SURFACE CURVES INWARD
• LIGHT RAYS COMING IN PARALLEL ALL REFLECT THROUGH
THE SAME POINT IN FRONT OF
THE MIRROR
• MAY BE A VIRTUAL OR REAL IMAGE & MAY BE INVERTED OR
UPRIGHT DEPENDING ON THE LOCATION OF THE OBJECT IN
RESPECT TO THE
FOCAL POINT
EX: MAKE-UP MIRRORS
FOCAL POINT
• THE POINT IN FRONT OF
THE MIRROR WHERE THE
REFLECTED RAYS MEET
PLANE MIRROR
CONCAVE MIRRORWITH AN OBJECT REFLECTED
FROM A DISTANCE
CONCAVE MIRROR RAYS, FOCAL POINT, AND CENTER
CONCAVE MIRROR
WITH THE OBJECT REFLECTED
LOCATED INSIDE THE FOCAL POINT
OBJECT
“VIRTUAL” IMAGE
CONCAVE MIRROROBJECT BETWEEN FOCAL POINT & MIRROR
CONVEX MIRROR
• SURFACE CURVES OUTWARD
• REFLECTED RAYS SPREAD OUT
FROM THE SURFACE
• IMAGE RIGHT SIDE UP AND
SMALLER THAN THE ORIGINAL OBJECT
• VIRTUAL IMAGE
• USED IN CARS & STORE SECURITY