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प्रश्न
Give a scientific reason.
Simple microscope is used for watch repairs.
उत्तर १
- When an object is put inside the focal length of a magnifying glass or simple microscope (convex lens), the larger and erect image appears on the same side of the lens as the object.
- By altering the distance between the object and the lens, the image can be obtained at the shortest distance of distinct vision. Thus, a watch repairer may see the minute parts of a watch more clearly with the use of a magnifying glass (a rudimentary microscope) than with the naked eye, and without putting any strain on the eye. As a result, watch repairers utilise a magnifying glass (a basic microscope) to repair the timepieces.
उत्तर २
- In a simple microscope, a convex lens with a small focal length is used.
- It produces a virtual, erect, and bigger image of an object.
- We can get a 20 times larger image of an object using a simple microscope.
Hence, watch repairers use a simple microscope while repairing watches.
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संबंधित प्रश्न
A converging lens has focal length of 12 cm. Calculate at what distance the object should be placed from the lens so that it forms an image at 48 cm on the other side of the lens.
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(c) What is the distance between the object and its image?
(d) Draw a ray diagram to show the image formation in this case.
At what distance from a concave lens of focal length 20 cm, should a 6 cm tall object be placed so that it forms an image at 15 cm from the lens ? Also determine the size of the image formed.
A student has obtained an image of a distant object on a screen to determine the focal length F1 of the given lens. His teacher, after checking the image, gave him another lens of focal length F2 and asked him to focus the same object on the same screen. The student found that to obtain a sharp image, he has to move the lens away from the screen. From this finding, we may conclude that both the lenses given to the student were :
(A) Concave and F1 < F2
(B) Convex and F1 < F2
(C) Convex and F1 > F2
(D) Concave and F1 > F2
A student was asked by his teacher to find the image distance for various object distance in case of a given convex lens. He performed the experiment with all precautions and noted down his observations in the following table:
| S. No. |
Object distance (cm) |
Image distance (cm) |
| 1 | 60 | 15 |
| 2 | 48 | 16 |
| 3 | 36 | 21 |
| 4 | 24 | 24 |
| 5 | 18 | 36 |
| 6 | 16 | 48 |
After checking the observations table the teacher pointed out that there is a mistake in recording the image distance in one of the observations. Find the serial number of the observations having faulty image distance.
(A) 2
(B) 3
(C) 5
(D) 6
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The lens A produces a magnification of, − 0.6 whereas lens B produces a magnification of + 0.6.
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What is the nature of lens B?
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A student wants to project the image of a candle flame on a screen 80 cm in front of a mirror by keeping the candle flame at a distance of 20 cm from its pole.
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Solve the following example.
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Solve the following example.
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The image of a candle flame formed by a lens is obtained on a screen placed on the other side of the lens. If the image is three times the size of the flame and the distance between lens and image is 80 cm, at what distance should the candle be placed from the lens? What is the nature of the image at a distance of 80 cm and the lens?
The focal length of a concave lens is 20 cm. At what distance from the lens should a 5 cm tall object be placed so that its image is formed at a distance of 15 cm from the lens? Also calculate the size of the image formed.
The magnification by a lens is -3. Name the lens and state how are u and v related?
What information about the nature of image is erect or inverted, do you get from the sign of magnification + or -?
