Advertisements
Advertisements
Question
The power of a lens is +2.0 D. Find its focal length and state the kind of lens.
Advertisements
Solution
P = + 2.0 D
P = `1/("F" ("in meter"))`
`=> "F" = 1/ "P" = 1/2`
F = 0.5 m or 50 cm
∵ Power is (+ve)
∴ It is a convex lens.
APPEARS IN
RELATED QUESTIONS
State power of a lens S.I. unit.
How unit of power related to focal length of a lens?
A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.
Find the focal length of a lens of power −2.0 D. What type of lens is this?
A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?
What is the focal length of a convex lens of focal length 30 cm in contact with a concave lens of focal length 20 cm? Is the system a converging or a diverging lens? Ignore thickness of the lenses.
(a) At what distance should the lens be held from the figure in order to view the squares distinctly with the maximum possible magnifying power?
(b) What is the magnification in this case?
(c) Is the magnification equal to the magnifying power in this case? Explain.
The focal length of a convex lens is 25 cm. What is its power?
The power of a lens is, −2 D. What is its focal length?
Name the type of lens whose power is positive.
The image of an object formed by a lens is real, inverted and of the same size as the object. If the image is at a distance of 40 cm from the lens, what is the nature and power of the lens ? Draw ray diagram to justify your answer.
