Advertisements
Advertisements
प्रश्न
Power of a lens is – 4D, then its focal length is
पर्याय
4m
–40m
–0.25 m
–2.5 m
Advertisements
उत्तर
– 0.25 m
APPEARS IN
संबंधित प्रश्न
Calculate the focal length of a corrective lens having power +2.5 D.
What does sign of power (+ve or –ve) indicate?
Define 1 dioptre of power of a lens.
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.
A combination of lenses for a camera contains two converging lenses of focal lengths 20 cm and 40 cm and a diverging lens of focal length 50 cm. Find the power and focal length of the combination.A optical instrument in which the above arrangement of convex lens is used is a convex lens used to burn paper by focusing sunlight.
The power of a lens is +2.0D. Its focal length should be :
The power of a lens is + 1.0 D is :
Surabhi from std. X uses spectacle. The power of the lenses in her spectacle is 0.5 D.
Answer the following questions from the given information:
- Identify the type of lenses used in her spectacle.
- Identify the defect of vision Surabhi is suffering from.
- Find the focal length of the lenses used in her spectacle.
The following diagram shows the object O and the image I formed by a lens. Copy the diagram and on it mark the positions of the lens LL’ and focus (F). Name the lens.
In what unit is the power of a lens expressed?
