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प्रश्न
Define the principal focus of a concave lens.
उत्तर
The principle focus of a concave lens is a point on the principle axis where all the reflected rays parallel to the principle axis appear to diverge.
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संबंधित प्रश्न
A small bulb is placed at the focal point of a converging lens. When the bulb is switched on, the lens produces:
(a) a convergent beam of light
(b) a divergent beam of light
(c) a parallel beam of light
(d) a patch of coloured light
How would you alter the above diagram to show how a converging lens can produce a beam of parallel rays of light.
Which type of lens is
a diverging lens? Explain your answer with diagrams.
When an object is placed 10 cm in front of lens A, the image is real, inverted, magnified and formed at a great distance. When the same object is placed 10 cm in front of lens B, the image formed is real, inverted and same size as the object.
What is the nature of lens A?
Out of the two lenses, one concave and the other convex, state which one will show the divergent action on a light beam. Draw diagrams to illustrate your answer.
Study the diagram below.
- Name the lens LL’.
- What are the points O and O' called ?
- Complete the diagram to form the image of the object AB.
- State three characteristics of the image.
State two applications of a concave lens.
Do we expect any change in the position, nature, and size of the image
(i) formed by a concave lens,
(ii) with a change in the position of the object?
The focal length of a lens is negative. In this case, state the kind of lens.
A parallel, oblique beam of light falls on a concave lens. Draw a diagram to show refraction of light through the lens.
