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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
10 A
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