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प्रश्न
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.
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उत्तर
The image formed by the lens is virtual, erect and diminished in size.
(a)(ii) Object distance (u) = -150 mm = -15 cm (sign convention)
Focal length (f) = -100 mm = -10 cm (sign convention)
Image distance (v) = ?
Applying the lens formula, we have:
`1/v-1/u=1/f`
`1/v-1/-15=1/-10`
`1/v+1/15=-1/10`
`1/v=1/10-1/15`
`1/v=(-3-2)/30`
`1/v=(-5)/30`
`v=-6 cm `
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संबंधित प्रश्न
A student focused the Sun rays using an optical device 'X' on a screen S as shown.
From this it may be concluded that the device 'X' is a (select the correct option)
(A) Convex lens of focal length 10 cm.
(B) Convex lens of radius of curvature 20 cm.
(C) Convex lens of focal length 20 cm.
(D) Concave mirror of focal length 20 cm.
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Name the spherical mirror which can produce a virtual and diminished image of an object.
A 2.0 cm tall object is placed 40 cm from a diverging lens of focal length 15 cm. Find the position and size of the image.
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Name the kind of mirror used to obtain
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(b) a virtual and enlarged image
(c) a real and diminished image, and
(d) a virtual and diminished image.
Explain the meaning of the terms focus and focal length in case of a convex mirror, with the help of suitable ray diagram.
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State two uses of a concave mirror.
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Select the correct option:
A concave mirror is made by cutting a portion of a hollow glass sphere of radius 30 cm. The focal length of the concave mirror is:
Define the following term:
concave mirror
Name the type of mirror used in the following situation:
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Support your answer with reason.
The distance from the center of curvature of the mirror to the pole is called the focal length of the mirror.
