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प्रश्न
Differentiate convex lens and concave lens.
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उत्तर
| Convex Lens | Concave Lens |
| 1. The lens which is thicker at the centre than at the edges. | 1. The lens is thinner at the centre than at the edges. |
| 2. Abeam of light passing through it, is converged to a point. | 2. A beam of light passing through it is diverged or spread out. |
| 3. It is called a converging lens. | 3. It is called a diverging lens. |
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संबंधित प्रश्न
(a) Draw a ray diagram to show the formation of an image by a convex lens when an object is placed in front of the lens between its optical centre and principal focus.
(b) In the above ray diagram, mark the object distance (u) and the image distance (v) with their proper signs (+ve or –ve as per the new Cartesian sign convention) and state how these distances are related to the focal length (f) of the convex lens in this case.
(c) Find the power of a convex lens which forms a real and inverted image of magnification –1 of an object placed at a distance of 20 cm from its optical centre.
If you focus the image of a distant object, whose shape is given below, on a screen using a convex lens, the shape of the image of this object on the screen would be:
(a)
(b)
(c)
(d)
Complete the following table:
| Instrument | Number of Convex Lenses |
Use |
| Simple Microscope | .............. | .............. |
| Compound Microscope | .............. | .............. |
| Telescope | .............. | .............. |
How could you find the focal length of a convex lens rapidly but approximately?
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
What type of images can a convex lens make?
When you focus the image of a distant flag, whose shape is given below, on a screen using a convex lens, the shape of the image as it appears on the screen is
(A)
(B)
(C)
(D)
Where should an object be placed in front of a convex lens to get a real image of the size of the object?
_______ times larger images can be obtained by using a simple microscope.
Find the odd one out and give its explanation.
