SPHERICAL MIRROR

Virtual ImagesVirtual Images are basically images which cannot be visually projected on a screen.

If this box gave off light, we could project an image of this box on to a screen provided the screen was on the SAME SIDE as the box.You would not be able to project the image of the vase or your face in a mirror on a screen, therefore it is a virtual image.

CONCLUSION: VIRTUAL IMAGES are ALWAYS on the OPPOSITE side of the mirror relative to the object.

Real ImageReal Images are ones you can project on to a screen.

For MIRRORS they always appear on the SAME SIDE of the mirror as the object.

object

image

The characteristics of the image, however, may be different from the original object. These characteristics are:•SIZE (reduced, enlarged, same size)•POSITION (same side, opposite side)•ORIENTATION (right side up, inverted)

Spherical Mirrors – Concave & Convex

Also called CONVERGING mirrorAlso called DIVERGING mirror

Converging (Concave) Mirror

Since the mirror is spherical it technically has a CENTER OF CURVATURE, C. The focal point happens to be HALF this distance.

We also draw a line through the center of the mirror and call it the PRINCIPAL AXIS.

C F P

(a) Rays parallel to the principal axis are reflected and they pass through the principal focus

(b) Rays passing through the principal focus (F) will move parallel to the principal axis after reflection

C F P

(c) Ray passing through the centre of curvature (C) are reflected back along their own paths because they are normal to the mirror.

C F P

FC P

I am parallel to the principal axis. Always draw me first

I am the Object

I am re

flected and

pass th

rough F.For me, I pass

through F first

I am reflected parallel to the principal axis

I pass through C

and I am reflected

back along my own

path

Now let us draw a ray diagram for an object beyond C

What is the nature and position of the image formed?1) Image is real but inverted.2) Image is between focus(F)

and center of curvature(C).

Imag

e

FC P

I am parallel to the principal axis. Always draw me first

I am the Object

I am re

flected and

pass th

rough

F.

For me, I pass

through F first

I am reflected parallel to the principal axis

Now let us draw a ray diagram for an object at C

I am

the

imag

e

What is the nature of image formed?1) The image is real , inverted and of same size.2) The image is formed at center of curvature.

FC P

I am parallel to the principal axis.

I am the Object

I am re

flected and

pass th

rough

F.

For me, I pass

through F first

I am reflected parallel to the principal axis

Now the object is between C and F

I am

the

imag

e no

w.

What is the nature of this image?1) The

image is real and magnified.

2) The position of image is beyond center of curvature

FC P

I am the Object

Now let us draw a ray diagram for an object at F

We will meet at in

finity to

form a real, inverted

magnified image.

FC P

I am the Object

I am reflected and

pass through F.

For m

e, I p

ass

thro

ugh F

first

I am reflected parallel to the principal axis

I pass through C and I am reflected

back along my own path

Now let us draw a ray diagram for an object between F and P

I am the image.

What is the nature of image formed?1) The image is

virtual , erect and magnified.

2) The is formed behind the mirror.

The Sky Mirror in Monte Carlo

USES OF CONCAVE MIRROR

Used in cars to provide strong parallel beams of light.

Used by females and males in makeup and shaving by them respectively. To provide enlarged and virtual image.

CONVEX MIRROR

Apparent Convergence of rays

2 f(f)

Focal ray

Parallel ray

Ray thru 2f

Image is:VirtualErectReducedAppears behind the mirror

Image by convex mirror when object beyond 2f

Parallel rays

Reflected rays

Virtual focus

Focal length = -Forms only virtual,

erect, reduced images betweenthe virtual focus and the mirror.

Dotted lines Shows the ApparentRay focus

Image formed by convex mirror when object is at infinity.

USES OF CONVEX MIRRORConvex Mirror is used in

the given images because:-

1) It help the driver to see the vehicles behind them.

2) It covers a large area as compared to plane mirror or concave mirror.

3) It creates erect and virtual image always

The Mirror EquationIs there any OTHER way to predict image characteristics

besides the ray diagram? YES!

One way is to use the MIRROR/LENS equation to CALCULATE the position of the image .

d0 = distance between pole and image d1= distance between pole and object

io ddf

111

MAGNIFICATIONMagnification produced by a spherical mirror

gives the relative extent to which the image of an object is magnified with respect to the object size.

It is expressed as the ratio of the height of the image(h2) to the height of the object(h1).

The magnification is also related to the object distance (u) and image distance(v).

M=h2/h1=-v/u

THANK YOUBy:- Kshitiz Rai

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