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प्रश्न
An object forms a virtual image which is 1/8th of the size of the object. If the object is placed at a distance of 40 cm from the convex mirror, calculate:
- the position of the image
- the focal length of the convex mirror.
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उत्तर
Let size of the object = h0 = x
Size of the image h1 = `"x"/8` = + 1.25 cm
Distance of the object from the converx mirror = u = - 40 cm
Distance of the image from the convex mirror = v = ?
(i) Magnification = m = `"h"_1/"h"_0 = - "v"/"u"`
`("x"/8)/"x" = - "v"/-40`
v = `"x"/"8x" xx 40 = 5` cm
(ii) Using mirror formula:
`1/"u" + 1/"v" = 1/"f"`
We have,
`1/-40 + 1/5 = 1/"f"`
`1/"f" = - 1/40 + 1/5`
`1/"f" = (- 1 + 8)/40 = 7/40`
⇒ f = `40/7 = 5.71` cm
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संबंधित प्रश्न
Explain the following term related to spherical lenses:- optical centre
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. |
What happens when a ray of light falls normally (or perpendiculary) on the surface of a plane mirror?
A coin placed at the bottom of a vessel appears to be raised when water is poured in the vessel.
In the following figure shows a concave mirror with its pole (P), focus (F) and centre of curvature (C). Draw a ray diagram to show the formation of the image of an object AB by the concave mirror.
Geometric centre of the spherical mirror is ______.
The image formed in a plane mirror is always inverted.
