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प्रश्न
An object of height 2 cm is placed at a distance of 20 cm in front of a concave mirror of a focal length of 12 cm. Find the position, size, and nature of the image.
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उत्तर १
The image is 30 cm in front of the mirror, 3 cm high, real, inverted and magnified.
उत्तर २
Object distance (u) = -20 cm
Focal length (f) = -12 cm
Image size (I) = 2 cm
Let the image distance be 'v' then
`1/u + 1/v = 1/f`
Or, `1/(-20) + 1/v = 1/(-12)`
Or, `1/v = -1/12 + 1/20 = (-5 + 3)/60`
Or, `1/v = -2/60`
Or, v = -30 cm
Now, `"Image size (I)"/"Object size (O)" = -"Image distnace (v)"/"Object distnace (u)"`
Or, `I/2 = -((-30)/-20)`
Or, I = -3 cm
∴ The image is 30 cm in front of the mirror.
The image is 3 cm high with the following characteristics:
- Real
- Inverted
- Magnified
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संबंधित प्रश्न
Define the following term in the context of spherical mirrors:- Principal axis
Match the items given in Column I with one or more items of Column II.
| Column I | Column II | ||
| (a) | A plane mirror | (i) | Used as a magnifying glass. |
| (b) | A convex mirror | (ii) | Can form image of objects spread over a large area. |
| (c) | A convex lens | (iii) | Used by dentists to see enlarged image of teeth. |
| (d) | A concave mirror | (iv) | The image is always inverted and magnified. |
| (e) | A concave lens | (v) | The image is erect and of the same size as the object. |
| (vi) | The image is erect and smaller in size than the object. |
Complete the following sentence:
All the distances are measured from the .......... of a spherical mirror.
A small object is placed 150 mm away from a diverging lens of focal length 100 mm.
(i) Copy the figure below and draw rays to show how an image is formed by the lens.
Figure
(ii) Calculate the distance of the image from the lens by using the lens formula.
What do you mean by the term dispersion?
How is a spherical mirror used to converge a beam of light at a point? Name the type of mirror used.
What is a spherical mirror?
A point light source is kept in front of a convex mirror at a distance of 40 cm. The focal length of the mirror is 40 cm. Find the position of image.
AB is the object, A1B1 is its image. MM' is the position of the mirror. Complete the ray diagram and find the position of the center of curvature and focus of the mirror. Also, measure the focal length.
Define the term Focus of a concave mirror.
