Advertisements
Advertisements
Question
What is the nature of a lens whose power is, −4 D?
Advertisements
Solution
Negative sign indicates it is a diverging lens. Therefore, the lens is concave in nature.
APPEARS IN
RELATED QUESTIONS
State power of a lens S.I. unit.
How unit of power related to focal length of a lens?
Define 1 dioptre of power of a lens.
Consider two statements A and B given below:
A: real image is always inverted
B: virtual image is always erect
Out of these two statements:
The lens A has a focal length of 25 cm whereas another lens B has a focal length of 60 cm. Giving reason state, which lens has more power: A or B.
What is the power of a convex lens lens whose focal length is 80 cm?
The power of a lens is + 0.2 D. Calculate its focal length.
The optician's prescription for a spectacle lens is marked +0.5 D. What is the:
(a) nature of spectacle lens?
(b) focal length of spectacle lens?
An object of height 4.25 mm is placed at a distance of 10 cm from a convex lens of power +5D. Find (i) the focal length of the lens, and (ii) the size of the image.
A convex lens of power 5 D and a concave lens of power 7.5 D are placed in contact with each other. What is the :
(a) power of this combination of lenses?
(b) focal length of this combination of lenses?
A convex lens of focal length 25 cm and a concave lens of focal length 10 cm are placed in close contact with one another.
(a) What is the power of this combination?
(b) What is the focal length of this combination?
(c) Is this combination converging or diverging?
A converging lens has a focal length of 50 cm. The power of this lens is:
State the condition for the following a ray passes undeviated through the lens .
Express the power (with sign) of a concave lens of focal length 20 cm.
How does focal length of a lens change when red light incident on it is replaced by violet light? Give reason for your answer.
A convex lens is of focal length 20 cm. Find its power.
If the lens is of focal length 25 cm. Calculate the power of the lens.
Focal length : metre : : power of lens : _______
Find the power of a convex lens of focal length of + 25 cm.
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?
