Advertisements
Advertisements
प्रश्न
On reducing the focal length of a lens, its power ______.
विकल्प
Decreases
Increases
Does not change
First increases then decreases.
Advertisements
उत्तर
On reducing the focal length of a lens, its power increases.
APPEARS IN
संबंधित प्रश्न
Find the power of a concave lens of focal length 2m.
A student uses a lens of focal length 40 cm and another of –20 cm. Write the nature and power of each lens
Define the term focal length of a lens.
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 double convex lens has focal length 25 cm. The radius of curvature of one of the surfaces is double of the other. Find the radii, if the refractive index of the material of the lens is 1.5.
A diverging lens of focal length 20 cm and a converging lens of focal length 30 cm are placed 15 cm apart with their principal axes coinciding. Where should an object be placed on the principal axis so that its image is formed at infinity?
Focal length : metre : : power of lens : _______
Find the power of a convex lens of focal length of + 25 cm.
A convex lens with radii of curvature R1 = R2 is immersed in water. Assuming that the refractive indices of glass and water are 3/2 and 4/3 respectively, its focal length f1 in comparison to that in air, f, is ______.
The same size images are formed by a convex lens when the object is placed at 20 cm or at 10 cm from the lens. The focal length of convex lens is ______ cm.
