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
Define 1 dioptre of power 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.
The focal length of a convex lens is 25 cm. What is its power?
What is the nature of a lens having a power of + 0.5 D?
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.
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.
How does focal length of a lens change when red light incident on it is replaced by violet light? Give reason for your answer.
Find the radius of curvature of the convex surface of a plano-convex lens, whose focal length is 0.3 m and the refractive index of the material of the lens is 1.5.
Increase in the converging power of eye lens cause ‘hypermetropia'
Define power of a lens. What is its unit? One student uses a lens of focal length 50 cm and another of –50 cm. What is the nature of the lens and its power used by each of them?
