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Very Short answer Questions
1. How do you get a virtual image using a concave
mirror?
A. If we place the object between pole and focus of
the concave mirror, then we will get a virtual image.
2. The magnification produced by a plane mirror is
+1. what does it mean?
A. Magnification is ratio of size of image to size of
object, so plane mirror's magnification is +1
means size of image and object are same for plane
mirror.
 2  2017
3. What are needed to form a shadow?
A. A source of light, an opaque object and a screen
are needed to form a shadow.
4. Show the formation of image with a ray diagram,
when an object is placed on the principl axis of a
concave mirror away from the centre of
curvature.
A. When the object is placed away from the centre of
curvature on the principal axis, the image will
form between C and F. Refer textbook for
diagram.
What are the laws of reflection?
Reflection of light by
Curved Surface
Key Points
1. Light travels in a straight line.
2. A source of light, an opaque object and a
screen are needed to form a shadow.
3. Fermat's principle: When light gets
reflected from a surface, it selects the path
that takes the least time.
4. According to laws of reflection of light,
i) The angle of incidence is equal to the angle
of reflection, and
ii) The incident ray, the normal to the mirror
at the point of incidence and the reflected
ray, all lie in the same plane.
5. The plane in which the incident ray, reflected
ray and normal will lie is the plane of reflection
6. In the formation of an image by a plane
mirror the size of the image is equal to the
size of the object.
7. Plane mirrors always produce virtual images
which are upright and located behind the mirror.
8. Plane mirror produces lateral inversion i.e.,
left becomes right and right becomes left.
9. When the rays after reflection if they actually
converge to form an image, it is called real image.
10. Real image can be received on a screen.
11. When the rays after reflection appear to diverge
from the mirror , it is called virtual image.
12. Virtual image cannot be received on a screen.
13. Laws of reflection are applicable to all types
of reflecting surfaces including spherical
surfaces.
14. Convex and concave mirrors are known
collectively as spherical mirrors, since their
curved reflecting surfaces are usually part
of the surface of a sphere
15. The reflecting surface of a spherical mirror
may be curved inwards or outwards.
16. A spherical mirror, whose reflecting surface
is curved inwards, that is, faces towards the
centre of the sphere, is called a concave mirror.
17. A spherical mirror, whose reflecting surface
is curved outwards, is called a convex mirror.
18. The schematic representation of these mirrors
is shown in Fig. You may note in these diagrams
that the back of the mirror is shaded
a) Concave mirror
(b) Convex mirror
19. A concave mirror can form a real or virtual image.
20. A convex mirror always form a r virtual
image for a real object.
21. The mid point (Geometrical centre) of the
mirror is called pole (P) of the mirror.
22. The horizontal line which passes through
the centre of curvature and pole is called
central axis /principal axis of the mirror.
23. The distance between Pole, P and Centre of
Curvature, C is radius of curvature (R) of
the mirror.
24. The rays coming for the sun parallel to the
principal axis of concave mirror con¬verge
at a point. This point is called Focus or
focal point (F) of the concave mirror.
25. The distance from the pole of the mirror to
the focus is called focal length of the mirror.
26. The relation between radius of curvature
(R) and focal length(f) of the mirror is R= 2f.
27. Identification of Image formed by spherical
mirrors can be made easy by drawing
minimum of two rays to form the object.
Rules to Draw ray Diagram
28. Any ray which passes parallel to the principal
axis, after reflection passes through the focal
point.
29. The ray going through the focal point and
falling on the mirror after reflection become
parallel to principle axis.
30. Any ray which passes through centre of
curvature after reflection it retraces
its path.
31. In case of concave mirror,
When the object is placed
10 th class
between pole and focus, the
Physics
position of the image is
behind the mirror, bigger,
erect and virtual.
32. In case of concave mirror, When the object
is placed on focus, the position of the image
is at infinity, bigger, inverted and real.
33. In case of concave mirror, When the object
is placed between focus and centre of
curvature, the position of the image is
beyond C, bigger, inverted and real.
34. In case of concave mirror, When the object
is placed on C, the position of the image is
at C, same size, inverted and real.
35. In case of concave mirror, When the object
is placed beyond C, the position of the
image is between focus and centre of
curvature, smaller, inverted and real.
36. Sign convention for parameters related to
mirror equation
37. All distances should be measured from the pole
38. The distances measured in the direction of
incident light its be taken positive and
those measured in the direction opposite to
incident light to be taken as negative.
39. Height of object (ho) and height of image
(hi) are positive it measured upwards from
the axis and negative it measured
downwards.
40. MIRROR FORMULA:
1/f = 1/u + 1/v
where f - focal length of the mirror
u- object distance from the mirror
v- image distance from the mirror
Focal length is always +ve for convex
mirror and -ve for concave mirror
41. Magnification for spherical mirrors (m):
magnification (m)= hi/ho
= -v/u
where, hi - height of image
ho - height of object
v - image distance
u - object distance
42. Solar cooker is the application of concave
mirror
43. Head lights of vehicles are application of
concave mirror, where these are used in
parabolic shape
44. Rear view mirror of vehicles is application
of convex mirror where the field of view is
large and also produces the erect and
diminished image.
Essay answer questions
1. What do you know about the terms given
below related to spherical mirrors?
a) pole
b) centre of curvature
c) focus
d) radius of curvature
e) focal length
f) principal axis
g) object distance
h) Image distance i) magnification -(AS1)
(or)
Define the terms mentioned in the above
question related to spherical mirrors- (AS1)
2. How do you verify the laws of reflection
using an experiment - (AS3)
3. How do you verify first law of reflection
using an experiment- (AS3)
4. How do you verify second law of reflection
using an experiment -(AS3)
5.
Find the plane of reflection
experimentally for an incident ray which
passes through the heads of the pins
pierced in front of the mirror- (AS3)
6. Describe an experiment to observe types of
images formed by a concave mirror and
measure the object distance and image
distance- (AS3)
(or)
Comment on the position and size of the
image when object is placed at different
positions of a concave mirror. (AS3)
7. Derive the mirror formula
(or)
Derive 1/f = 1/u + 1/v ?
8. Draw and explain the process of formation
of image with a pinhole camera—(AS5)
9. Describe an activity to find the normal to a
curved surface. (AS1)
10. An object of 4cm in size is placed at 25cm
intrant of a concave mirror of focal length
15cm. At what distance from the mirror
should be a screen be placed in order to
obtain a sharp image? Find the nature and
size of image.
Short answer Questions
1. State the laws of reflection? (AS1)
(or)
What are the laws of reflection? (AS 1)
2. How do you find the focal length of a
concave mirror? (ASl)
3. Find the distance of the image when an
object is placed on the principal axis at a
distance of 10cm in front of a concave mirror
whose radius of curvature is 8cm? (ASl)
4. State the difference between convex and
concave mirrors? (AS l)
(or)
Distinguish between convex and concave
mirrors. (AS1)
5. Distinguish between real and virtual
images. (AS1)
6. Write the rules for sign convention of
spherical mirrors. (AS 1)?
7. Give the consequences, if there are no spherical
mirrors in our day to day life.(AS 2)
(or)
How would our daily life be without
spherical mirrors?.
9. By observing steel vessels and different
images in them, surya, a third class student,
asked us elder sister vidya same questions,
what may be these questions? (AS2)
10. Collect the information of history of
spherical mirrors in human civilization.
11. Explain the process of formation of image
with a pinhole camera? (AS5)
12. Explain the process of making a solar
cooker/heater. (AS5)
(or)
Make a solar heater/cooker and explain the
process of making. (AS5)
13. How should we place the object in front of
a concave mirror to form the image on the
object itself ? (AS5)
(or)
To form the image on the object itself, how
should we place the object intrant of a
concave mirror? Explain with a ray
diagram? (AS5)
14. How do you appreciate the role of spherical
mirrors in daily life? (AS6)
(or)
what are the applications of spherical
mirrors on daily life? (AS6)
15. How do you appreciate the use of reflection
of light by a concave mirror in making of
TV antenna diskes? (AS6)
16. Have you ever observed the image of the
sky in rain water pools on earth? Explain
the reflection of light in this context?
17. Discuss the merits and demerits of using
mirrors in building elevation?(AS7)
(or)
What are the advantages and disadvantages
of using mirrors in building elevation?
18. A convex mirror with a radius of curvature
of 3m is used as rear view in an
automobile. If a bus is located at 5m from
this mirror, find the position, nature and
size of the image. (AS7)
19. An object is placed at a distance of 10cm from
a convex mirror of focal length 15cm. Find
the position and nature of the image. (AS7)
20. Write any two uses of convex and concave
mirrors in our daily life?(AS7)
21. What are the characteristics of image
formed by a plane mirror. (AS 1)
22. What is magnification? write the formula.
23. Why does an image suffer lateral
inversion? (AS2)
A. The light rays come from object get
reflected from the plane mirror and reach
our eye. our eye feels that the ray is coming
from inside the mirror. That is why the
right of object looks like left in the image.
24. How does an image form due to convex
mirror? Draw the ray diagram.
A i) The parallel rays coming from distance
object tend to diverge after reflection
ii) If we extend the reflected rays backwards
they meet at 'F' i.e,, focal point of the
convex mirror. Refer textbook for diagram.
P. Sanjeev
PGT (Physical Science)
Karimnagar