Advertisements
Advertisements
Question
The lens mentioned in 6(b) above is of focal length 25cm. Calculate the power of the lens.
Advertisements
Solution
Focal length of a convex lens is always positive.
Given: f = +25 cm
`therefore P=1/f`
`P=1/25`
`P=+0.04D`
APPEARS IN
RELATED QUESTIONS
What does sign of power (+ve or –ve) indicate?
What is the nature of a lens whose power is, −4 D?
Two lenses A and B have focal lengths of +20 cm and, −10 cm, respectively.
(a) What is the nature of lens A and lens B?
(b) What is the power of lens A and lens B?
(c) What is the power of combination if lenses A and B are held close together?
What do you understand by the power of a lens? Name one factor on which the power of a lens depends.
What is the unit of power of a lens? Define the unit of power of a lens.
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.
A double convex lens has two surfaces of equal radii R and refractive index \[m = 1 \cdot 5\]
A symmetric double convex lens in cut in two equal parts by a plane perpendicular to the principal axis. If the power of the original lens was 4 D, the power a cut-lens will be
The power of convex lens of focal length 20 cm is ______.
