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प्रश्न
What kind of mirror can have a focal length of, −20 cm?
उत्तर
A concave mirror can have a focal length of -20 cm. The reason being, a concave mirror has a negative focal length(according to the 'new cartesian sign convention').
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संबंधित प्रश्न
To construct a ray diagram we use two rays of light which are so chosen that it is easy to determine their directions after reflection from the mirror. Choose these two rays and state the path of these rays after reflection from a concave mirror. Use these two rays to find the nature and position of the image of an object placed at a distance of 15 cm from a concave mirror of focal length 10 cm.
If an object is placed at the focus of a concave mirror, where is the image formed?
Explain why, concave mirrors are used as shaving mirrors.
The focal length of a small concave mirror is 2.5 cm. In order to use this concave mirror as a dentist's mirror, the distance of tooth from the mirror should be:
(a) 2.5 cm
(b) 1.5 cm
(c) 4.5 cm
(d) 3.5 cm
If an object of 10 cm height is placed at a distance of 36 cm from a concave mirror of focal length 12 cm, find the position, nature and height of the image.
If the image formed is always virtual, the mirror can be:
(a) concave or convex
(b) concave or plane
(c) convex or plane
(d) only convex
Answer the following question:
An object is placed at a distance of 30 cm from a concave lens of focal length 30 cm.
(i) Use the lens formula to determine the distance of the image from the lens.
(ii) List four characteristics of the image (nature, position, size, erect/inverted) in this case.
(iii) Draw a labelled diagram to justify your answer of the part (ii)
Name the mirror(s) that can give (i) an erect and enlarged image, (ii) same sized, inverted image
What is a concave and convex mirror?
Which type of mirror is used in the following?
Shaving mirror
