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प्रश्न
An object is placed at a distance of 60 cm from a concave lens of focal length 30 cm.
(i) Use the lens formula to find the distance of the image from the lens.
(ii) List four characteristics of the image (nature, position, size, erect/inverted) formed by the lens in this case.
(iii) Draw a ray diagram to justify your answer of the part (ii).
उत्तर
We have,
(i) Object distance, u= —60 cm Focal length of the concave lens, f= —30 cm Using lens formula,
`1/"v"-1/"u" = 1/"f"`
`1/"v" - 1/((-60)) =1/((-30))`
`1/"v"=(-1)/30-1/60`
`1/"v"=(-3)/60`
v = -20 cm
The image will be formed at a distance of 20 cm in front of the lens.
(ii) Nature of the image is virtual. The position of the image is between F1 and optical center 0. Size of the image is diminished. The image is Erect.
(iii)
संबंधित प्रश्न
A converging lens is used to produce an image of an object on a screen,object on a screen. What change is needed for the image to be formed nearer to the lens?
(a) increase the focal length of the lens
(b) insert a diverging lens between the lens and the screen
(c) increase the distance of the object from the lens
(d) move the object closer to the lens
Which type of lens is
a diverging lens? Explain your answer with diagrams.
Out of the two lenses, one concave and the other convex, state which one will show the divergent action on a light beam. Draw diagrams to illustrate your answer.
How will you differentiate between a convex and a concave lens by looking at
- a distant object,
- a printed page?
A virtual diminished image is formed when an object is placed between the optical centre and the principal focus of a lens.
(i) Name the type of lens which forms the above image.
(ii) Draw a ray diagram to show the formation of the image with the above stated characteristics.
An object is placed at a distance 24 cm in front of a convex lens of focal length 8 cm.
(i) What is the nature of the image so formed?
(ii) Calculate the distance of the image from the lens.
(iii) Calculate the magnification of the image.
Distinguish between concave and convex lens.
Define the principal focus of a concave lens.
Define the term principal foci as applied to a concave lens. Illustrate your answer with the aid of proper diagrams. Show the focal length of the lens in the diagram.
In a reading glass what is the position of the object with respect to the concave lens used?
