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प्रश्न
Suppose you have three concave mirrors A, B and C of focal lengths 10 cm, 15 cm and 20 cm. For each concave mirror you perform the experiment of image formation for three values of object distance of 10 cm, 20 cm and 30 cm. Giving reason answer the following:
(a) For the three object distances, identify the mirror/mirrors which will form an image of magnification – 1.
(b) Out of the three mirrors identify the mirror which would be preferred to be used for shaving purposes/makeup.
(c) For the mirror B draw ray diagram for image formation for object distances 10 cm and 20 cm.
उत्तर
(a) In case of concave mirror, a real and inverted image of same size is formed as that of object, when object is placed at a distance of 2F (R). Hence, in case of mirror A when object is placed at 20 cm , and in case of mirror B, when object is placed at 30 cm, the image formed will be of same size as that of object. Thus, magnification in both these cases will be −1.
(b) The mirror C, with focal length of 20 cm will be preferred to be used for shaving purposes/makeup. As within this focal length, enlarged and erect image will be formed.
(c)
(i) When the object is at 10 cm from the mirror
(ii) When the object is at 20 cm from the mirror
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संबंधित प्रश्न
Draw a ray diagram to show the path of the refracted ray in each of the following cases:-
A ray of light incident on a concave lens is
(i) passing through its optical centre.
(ii) parallel to its principal axis.
(iii) directed towards its principal focus.
Find the focal length of a concave mirror whose radius of curvature is 32 cm.
Fill in the following blank with suitable word:
A concave mirror .......... rays of light whereas convex mirror ............ rays
If an object is placed at the focus of a concave mirror, where is the image formed?
The image formed by a concave mirror is real, inverted and highly diminished (much smaller than the object). The object must be:
(a) between pole and focus
(b) at focus
(c) at the centre of curvature
(d) at infinity
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.
At what distance from a concave mirror of focal length 10 cm should an object be placed so that:
its virtual image is formed 20 cm from the mirror?
An object is placed 15 cm from (a) a converging mirror, and (b) a diverging mirror, of radius of curvature 20 cm. Calculate the image position and magnification in each case.
A convex mirror is used as a shaving mirror.
Pick out the concave and convex mirrors from the following and tabulate them.
Rear-view mirror, Dentist’s mirror, Torchlight mirror, Mirrors in shopping malls, Make-up mirror.
