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Question
If the image formed by a mirror for all positions of the object placed in front of it is always erect and diminished, what type of mirror is it? Draw a ray diagram to justify your answer. Where and why do we generally use this type of mirror?
Solution
A convex mirror always produces an erect and diminished image of the object placed in front of it irrespective of the position of the object.
Consider a case in which an object is placed anywhere between pole (P) and infinity in front of a convex mirror. The ray diagram is as shown:-
A virtual, erect and diminished image will be formed behind the mirror between the pole (P) and focus (F) of the mirror.
As a convex mirror gives a wide field of view, it is used as a rear view mirror in vehicles.
It enables the driver to view a much larger area of the traffic behind. It is also used as shop security mirrors.
RELATED QUESTIONS
Name the mirror that can give an erect and enlarged image of an object.
Draw the following diagram in your answer book and show the formation of image of the object AB with the help of suitable rays:
between its pole and focus
Describe the nature, size and position of the image formed in each case.
State one use of concave mirror bases on the formation of image as in case (i) above.
The real image formed by a concave mirror is smaller than the object if the object is:
(a) between centre of curvature and focus
(b) at a distance greater than radius of curvature
(c) at a distance equal to radius of curvature
(d) at a distance equal to focal length
A concave mirror has a focal length of 25 cm. At which of the following distance should a person hold his face from this concave mirror so that it may act as a shaving mirror?
(a) 45 cm
(b) 20 cm
(c) 25 cm
(d) 30 cm
Give reason for your choice.
Name the mirror which can give:
an erect and enlarged image of an object.
A student obtained a sharp inverted image of a distant tree on a screen placed in front of the concave mirror. He then removed the screen and tried to look into the mirror. He would now see
(A) a very blurred image on the wall opposite to the mirror
(B) an erect and magnified image of the tree in the mirror
(C) no image as the screen has been removed
(D) a highly diminished inverted image of the tree at the focus of the mirror.
To find the focal length of a concave mirror Rahul focuses a distant object with this mirror. The chosen object should be
(1) a tree
(2) a building
(3) a window
(4) the sun
Rays from Sun converge at a point 15 cm in front of a concave mirror. Where should an object be placed so that size of its image is equal to the size of the object?
The concave reflecting surface of a torch got rusted. What effect would this have on the beam of light from the torch?
