Advertisements
Advertisements
Question
The focal length of a double convex lens is equal to the radius of curvature of either surface. What is the refractive index of its material?
Advertisements
Solution
`1/"f" = ("n"-1) (1/"r"_1 + 1/"r"_2)`
`1/"f" = ("n"-1) (1/"f" + 1/"f")`
`("n"-1) = 1/2`
∴ n = 1.5
APPEARS IN
RELATED QUESTIONS
What is meant by a power of a lens? Define its SI unit.
What does sign of power (+ve or –ve) indicate?
State power of a lens S.I. unit.
Find the power of a concave lens of focal length 2m.
What is the power of a convex lens of focal length 0.5 m?
The power of a combination of two lenses X and Y is 5 D. If the focal length of lens X be 15 cm :
(a) calculate the focal length of lens Y.
(b) state the nature of lens Y.
Express the power (with sign) of a concave lens of focal length 20 cm.
Define power of a lens. Write its units. Deduce the relation `1/f =1/f_1 +1/f_2`for two thin lenses kept in contact coaxially.
A convex lens is of focal length 20 cm. Find its power.
The power of convex lens of focal length 20 cm is ______.
