Light

LIGHT : MIRRORS AND LENSES

LIGHT•Always travels in a straight line. This is the rectilinear propagation of light •Speed = 300,000 m/s•Travels in the form of wavelength

HITTING ANY SURFACE

When light hits any surface it may

1. Bounce back

2. Absorb

3. Pass through

REFLECTIONWhen light hits any surface and bounces back ,it is called reflection . There may be two types of reflection :Diffuse reflection Clear reflection

DIFFUSE REFLECTION From a rough

surface The rays may go

in any direction Image generally

not formed The surface will

not act as a mirror

CLEAR REFLECTION From smooth

and shiny surface

An image is formed

The surface will act as a mirror

NATURES OF IMAGES

Real : An image which forms on a screen

Virtual : An image which is formed inside the mirror

Erect :straight

Inverted : an image which is not straight

Lateral inversion : when left side appears on right and right appears on left side

REFLECTION IN A PLANE MIRROR

•NATURE OF THE IMAGE : •Laterally inverted•Erect•Same size•Distance between object and the mirror is same as the distance between the image and the mirror•Virtual

surface normal

sameangleincident ray exit ray

reflected ray

LAWS OF REFLECTION

•Angle of incidence = Angle of reflection•Normal , incident ray and the reflected ray , they all lie on the same plane.

Parallel rays

Reflected rays

RealFocus

Focal length = +Forms real, inverted,Reduced or enlarged

Image. Also formsVirtual, erect,

Enlarged images.

NATURE OF THE IMAGEOBJECT

IMAGE NATURE

BETWEEN P AND F

BEHIND THE MIRROR

ERECT,VIRTUAL,ENLARGED

AT F NO IMAGE -

BETWEEN C AND F

BEYOND C INVERTED,REAL,LARGE

AT C AT C INVERTED,SAME SIZE ,REAL

BEYOND C BETWEEN C AND F

INVERTED, REAL,SMALL

Parallel rays

Reflected rays

Virtual focus

Focal length = -Forms only virtual,

erect, reduced images betweenthe virtual focus and the mirror.

NATURE OF THE IMAGEOBJECT IMAGE NATUREBETWEEN P AND F

BETWEEN P AND F(INSIDE THE MIRROR)

VIRTUAL,ERECT,SMALL

AT F BETWEEN P AND F(INSIDE THE MIRROR)

VIRTUAL,ERECT,SMALL

BETWEEN C AND F

BETWEEN P AND F(INSIDE THE MIRROR)

VIRTUAL,ERECT,SMALL

AT C BETWEEN P AND F(INSIDE THE MIRROR)

VIRTUAL,ERECT,SMALL

BEYOND C BETWEEN P AND F(INSIDE THE MIRROR)

VIRTUAL,ERECT,SMALL

focus (f)focus (f) 2 f2 fx x x x

Parallel rayPasses thruThe focus

Focal ray

Refracts parallelTo principal axis

A ray thru theCenter of the

lenses

Remains unbent

NATURE OF THE IMAGEOBJECT

IMAGE NATURE

BETWEEN P AND F

BEHIND THE MIRROR

ERECT,VIRTUAL,ENLARGED

AT F NO IMAGE -

BETWEEN C AND F

BEYOND C INVERTED,REAL,LARGE

AT C AT C INVERTED,SAME SIZE ,REAL

BEYOND C BETWEEN C AND F

INVERTED, REAL,SMALL

f2 f f 2 fFocal ray

Parallel ray

Ray thru center

Image is:VirtualErectReducedAppears on sameSide as object

NATURE OF THE IMAGEOBJECT IMAGE NATUREBETWEEN P AND F

BETWEEN P AND F(INSIDE THE MIRROR)

VIRTUAL,ERECT,SMALL

AT F BETWEEN P AND F(INSIDE THE MIRROR)

VIRTUAL,ERECT,SMALL

BETWEEN C AND F

BETWEEN P AND F(INSIDE THE MIRROR)

VIRTUAL,ERECT,SMALL

AT C BETWEEN P AND F(INSIDE THE MIRROR)

VIRTUAL,ERECT,SMALL

BEYOND C BETWEEN P AND F(INSIDE THE MIRROR)

VIRTUAL,ERECT,SMALL