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प्रश्न
Which of the following can make a parallel beam of light from a bulb falls on it?
(a) concave mirror as well as concave lens
(b) convex mirror as well as concave lens
(c) concave mirror as well as convex lens
(d) concave mirror as well as convex lens
उत्तर
Concave mirror as well as Convex lens
When an object is placed at the focus of a concave mirror (convex lens), the reflected (refracted) light rays are always parallel to each other and to the principal axis.
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संबंधित प्रश्न
Explain why, a ray of light passing through the centre of curvature of a concave mirror gets reflected back along the same path.
If an object is placed at a distance of 8 cm from a concave mirror of focal length 10 cm, discuss the nature of the image formed by drawing the ray diagram.
With the help of a labelled ray diagram, describe how a converging mirror can be used to give an enlarged upright image of an object.
What is the position of the image when an object is placed at a distance of 20 cm from a concave mirror of focal length 20 cm?
How can a concave mirror be used to obtain a virtual image of an object? Draw a diagram to illustrate your answer.
In which equipment/s do you find ___________________
Study the following ray diagram and list two mistakes committed by the student while tracing it. Rectify these mistakes by drawing the correct ray diagram to show the real position and size of the image corresponding to the position of the object AB.
The ENT doctor uses a ______.
The focal length of a concave mirror is 5cm. Its radius of curvature is ______.
A student took three concave mirrors of different focal lengths and performed the experiment to see the image formation by placing an object at different distance with these mirrors as shown in the following table.
| Case No. | Object-distance | Focal length |
| I | 45 cm | 20 cm |
| II | 30 cm | 15 cm |
| III | 20 cm | 30 cm |
Now answer the following questions:
(a) List two properties of the image formed in Case I.
(b) In which one of the cases given in the table, the mirror will form real image of same size and why?
(c) Name the type of mirror used by dentists. Given reason why do they use such type of mirrors.
OR
(c) Look at the table and identify the situation (object distance and focal length) which resembles the situation in which concave mirrors are used as shaving mirrors? Draw a ray diagram to show the image formation in this case.
