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प्रश्न
What is a lens?
उत्तर
A lens is an optical device that transmits and refracts a ray of light, and converges or diverges a beam of light.
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संबंधित प्रश्न
A beam of light travelling in a rectangular glass slab emerges into air. Draw a ray-diagram indicating the change in its path.
Draw a labelled ray diagram to show how a ray of light passes through a parallel sided glass block:
if it hits the glass block at an angle other than 90° (that is, obliquely to the glass block).
Fill in the following blank with suitable word:
Parallel rays of light are refracted by a convex lens to a point called the ........
Describe with the help of a ray-diagram, the size, nature and position of the image formed by a convex lens when an object is placed beyond 2f in front of the lens.
With the help of a labelled diagram explain how a convex lens converges a beam of parallel light rays. Mark the principal axis, optical centre, principal focus and focal length of the convex lens on the diagram.
A convex lens of focal length 15 cm produces a magnification of +4. The object is placed:
(a) at a distance of 15 cm
(b) between 15 cm and 30 cm
(c) at less than 15 cm
(d) beyond 30 cm
A camera fitted with a lens of focal length 50 mm is being used to photograph a flower that is 5 cm in diameter. The flower is placed 20 cm in front of the camera lens.
At what distance from the film should the lens be adjusted to obtain a sharp image of the flower?
Draw a diagram to represent the second focus of a convex lens.
State the position of object, position of image, nature of image when: Convex lens is used as an erecting lens in terrestrial telescope.
_______ is a combination of two convex lenses with small focal length.
