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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
Name the spherical mirror which can produce a real and diminished image of an object.
An optical device has been given to a student and he determines its focal length by focusing the image of the sun on a screen placed 24 cm from the device on the same side as the sun. Select the correct statement about the device.
(A) Convex mirror of focal length 12 cm
(B) Convex lens of focal length 24 cm
(C) Concave mirror of focal length 24 cm
(D) Convex lens of focal length 12 cm
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