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प्रश्न
In a certain murder investigation, it was important to discover whether the victim was long-sighted or short-sighted. How could a detective decide by examining his spectacles?
उत्तर
(a) If the victim's spectacles are fitted with convex lens, the detective can conclude that the victim was long-sighted. A person suffering from long-sightedness, or hypermetropia, wears spectacles with convex lenses to correct the defect.
(b) If the victim's spectacles are fitted with concave lens, the detective can conclude that the victim was short-sighted. A person with short-sightedness, or myopia, wears spectacles with concave lenses to correct the defect.
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संबंधित प्रश्न
To determine the approximate focal length of the given convex lens by focussing a distant object (say, a sign board), you try to focus the image of the object on a screen. The image you obtain on the screen is always
(a) erect and laterally inverted
(b) erect and diminished
(c) inverted and diminished
(d) virtual, inverted and diminished
An object is placed at a distance of 15 cm from a convex lens of focal length 20 cm. List four characteristics (nature, position, etc.) of the image formed by the lens.
A beam of light travelling in a rectangular glass slab emerges into air. Draw a ray-diagram indicating the change in its path.
Fill in the following blank with suitable word:
The image in a convex lens depends upon the distance of the ........... from the lens.
What is a lens?
Distinguish between a convex lens and concave lens. Which of the two is a converging lens : convex lens of concave lens?
The image obtained while finding the focal length of convex lens is ....................
State the position of object, position of image, nature of image when: Convex lens is used as objective lens of photographic camera.
Can a normal convex lens behave like a concave lens and vice-versa?
Define the principal focus of a convex lens.
