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प्रश्न
A converging mirror, forms three times magnified virtual image when an object is placed at a distance of 8 cm from it. Calculate:
- the position of the image
- the focal length of the mirror.
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उत्तर
Let size of the object = ho = x
Size of image = h1= +3 x (Virtual image)
Distance of the object from the mirror = u = -8 cm
Distance of the image from the mirror = v = ?
Focal length of the mirror = f = ?
(i) Magnification = m = `"h"_1/"h"_0 = - "v"/"u"`
`=> "3x"/"x" = "-v"/-8`
v = 8 × 3 = 24 cm
(ii) Using mirror formula:
`1/"u" + 1/"v" = 1/"f"`
`1/-8 + 1/24 = 1/"f"`
`1/"f" = - 1/8 + 1/24`
`1/"f" = (- 3 + 1)/24 = (-2)/24 = - 1/12`
⇒ f = - 12 cm
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संबंधित प्रश्न
An object 1.5 cm high when placed in front of a concave. the mirror produces a virtual image 3 cm high. If the object is placed at a distance of 6 cm from the pole of the mirror, calculate:
- the position of the image
- the focal length of the mirror.
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(i) What is the angle of incidence?
(ii) What is the angle of reflection?
(iii) What is the total angle turned by the ray of light?
(iv) What is the angle between the incident and the reflected rays?
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