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प्रश्न
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.
उत्तर
(i) As for convex lens, if |u| > | f | then real and inverted image is formed and as |u| > 2| f | then it is diminished.
(ii) `1/v - 1/u = 1 /f`
`1/v = 1/u + 1 /f`
`1/v = (f+u)/(uf)`
`⇒ v =(uf)/(f+u)`
= `((-24)(8))/((8)+(-24))`
= `(-24xx8)/(-16)`
= `(-192)/-16`
= 12 cm
(iii) m = `v/u = 12/-24 = -0.5`
The negative sign signifies an inverted image.
संबंधित प्रश्न
If the numerical value of the power of this lens is 10 D, what is its focal length in the Cartesian system ?
Where must the object be placed for the image formed by a converging lens to be:
real, inverted and smaller than the object?
An illuminated object is placed at a distance of 20 cm from a converging lens of focal length 15 cm. The image obtained on the screen is:
(a) upright and magnified
(b) inverted and magnified
(c) inverted and diminished
(d) upright and diminished
An object is placed 10 cm from a lens of focal length 5 cm. Draw the ray diagrams to show the formation of image if the lens is converging,
State one practical use each of convex mirror, concave mirror, convex lens and concave lens.
When a fork is seen through lenses A and B one by one, it appears as shown in the diagrams. What is the nature of (i) lens A, and (ii) lens B? Give reason for your answer.
The power of a concave lens is 10 D and that of a convex lens is 6 D. When these two lenses are placed in contact with each other, the power of their combination will be :
(a) +16 D
(b) +4 D
(c) −16 D
(d) −4 D
What kind of lens is used to correct
short-sightedness
A person cannot see distant objects clearly. His vision can be corrected by using the spectacles containing:
(a) concave lenses
(b) plane lenses
(c) contact lenses
(d) convex lenses
Study the diagram below.
- Name the lens LL’.
- What are the points O and O' called ?
- Complete the diagram to form the image of the object AB.
- State three characteristics of the image.
