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प्रश्न
Find the nature, position and magnification of the images formed by a convex lens of focal length 0.20 m if the object is placed at a distance of:
0.15 m
उत्तर
u = -15 cm
f = 20
Substituting these values in the lens formula, we get:
`1/f=1/v-1/u`
`1/20=1/v-1/-15`
`1/20=1/v+1/15`
`1/20-1/15=1/v`
`1/v=(3-4)/60`
`1/v=-1/60`
v=-60 cm
The image will be formed at a distance of 60 cm in front of the mirror.
`m=v/u`
⇒`m=(- 60)/-15`
⇒m=4
Magnification is positive; therefore, the image is virtual and
erect.
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संबंधित प्रश्न
(a) Draw a ray diagram to show the formation of an image by a convex lens when an object is placed in front of the lens between its optical centre and principal focus.
(b) In the above ray diagram, mark the object distance (u) and the image distance (v) with their proper signs (+ve or –ve as per the new Cartesian sign convention) and state how these distances are related to the focal length (f) of the convex lens in this case.
(c) Find the power of a convex lens which forms a real and inverted image of magnification –1 of an object placed at a distance of 20 cm from its optical centre.
An object is placed at a distance of 15 cm from a concave lens of focal length 30 cm. List four characteristics (nature, position, etc.) of the image formed by the lens.
Write one condition where it does not bend when entering a medium of different optical density.
What type of lens would you use as a magnifying glass? How close must the object be to the lens?
Find the position and nature of the image of an object 5 cm high and 10 cm in front of a convex lens of focal length 6 cm.
Calculate the focal length of a convex lens which produces a virtual image at a distance of 50 cm of an object placed 20 cm in front of it.
What kind of lens can form:
an erect magnified image?
A convex lens forms an inverted image of size same as that of the object which is placed at a distance 60 cm in front of the lens. Find: The position of image
_______ times larger images can be obtained by using a simple microscope.
Differentiate convex lens and concave lens.
