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Why are concave mirrors used in solar devices?

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प्रश्न

Why are concave mirrors used in solar devices? 

लघु उत्तरीय
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उत्तर

A concave mirror is also known as a converging mirror because of its ability to focus parallel rays of light at a single point on its focal plane. This property is used in solar devices. Parallel rays from the Sun, when reflected by the concave mirror, are focused at a particular point, generating a significant amount of heat. This heat is essential for the proper functioning of solar devices, such as solar cookers or solar furnaces. 

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अध्याय 11: Reflection of Light - Exercise [पृष्ठ १२७]

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बालभारती Science and Technology [English] 9 Standard Maharashtra State Board
अध्याय 11 Reflection of Light
Exercise | Q 1. c. | पृष्ठ १२७

संबंधित प्रश्न

A student has obtained the image of a distant object with a concave mirror to determine its focal length. If he has selected a well-illuminated red building as object, which of the following correctly describes the features of the image formed?

(A) Virtual, inverted and diminished image in red shade

(B) Real, erect and diminished image in pink shade

(C) Real, inverted and diminished image in red shade

(D) Virtual, erect and enlarged image in red shade


We wish to obtain an erect image of an object, using a concave mirror of focal length 15 cm. What should be the range of distance of the object from the mirror? What is the nature of the image? Is the image larger or smaller than the object? Draw a ray diagram to show the image formation in this case.


An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focused image can be obtained? Find the size and the nature of the image.


To construct a ray diagram we use two rays which are so chosen that it is easy to know their directions after reflection from the mirror. List two such rays and state the path of these rays after reflection in case of concave mirrors. Use these two rays and draw ray diagram to locate the image of an object placed between pole and focus of a concave mirror.


A 3 cm tall object is placed 18 cm in front of a concave mirror of focal length 12 cm. At what distance from the mirror should a screen be placed to see a sharp image of the object on the screen. Also calculate the height of the image formed.


If the focal length of a convex mirror is 25 cm, what is its radius of curvature?


Fill in the following blank with suitable word:  

 Parallel rays of light are reflected by a concave mirror to a point called the ..........


 Define (i) principal focus of a concave mirror, and (ii) focal length of a concave mirror.


Which kind of mirror is used in the headlights of a car? Why is it used for this purpose?


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. 

 


An object of 5.0 cm size is placed at a distance of 20.0 cm from a converging mirror of focal length 15.0 cm. At what distance from the mirror should a screen be placed to get the sharp image? Also calculate the size of the image.


An object is placed at a large distance in front of a concave mirror of radius of curvature 40 cm. The image will be formed in front of the mirror at a distance: 

(a) 20 cm
(b) 30 cm
(c) 40 cm
(d) 50 cm


A student has focused the image of a candle flame on a white screen using a concave mirror. The situation is as given below:

Length of the flame = 1.5 cm

Focal length of the mirror = 12 cm

Distance of flame from the mirror = 18 cm

If the flame is perpendicular to the principal axis of the mirror, then calculate the following:

  1. Distance of the image from the mirror
  2. Length of the image

If the distance between the mirror and the flame is reduced to 10 cm, then what would be observed on the screen? Draw ray diagram to justify your answer for this situation.


In which of the following, the image of an object placed at infinity will be highly diminished and point sized?


While looking at the above diagram, Nalini concluded the following.

  1. the image of the object will be a virtual one.
  2. the reflected ray will travel along the same path as the incident ray but in opposite direction.
  3. the image of the object will be inverted.
  4. this is a concave mirror and hence the focal length will be negative.

Which one of the above statements are correct?


An erect and enlarged image can be formed by


To obtain an image twice the size of the object, between which two points related to a concave mirror should an object be placed?


Which type of mirror is used in the following? 

Floodlights


State the different positions of the source of light with respect to the concave mirror in Projector lamps.

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