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प्रश्न
Find the nature, position and magnification of the images formed by a convex lens of focal length 0.20 m if the object is placed at a distance of:
0.25 m
उत्तर
u = -25 cm
f = 20 cm
⇒`1/f=1/v-1/u`
⇒`1/20=1/v-1/-25`
⇒`1/v=1/200-1/25`
⇒`1/v=(5-4)/100`
⇒`1/v=1/100`
⇒`v=100` cm
The image will be formed at a distance of 100 cm behind the mirrror.Magnification,
⇒`m=v/u`
⇒`m=100/-25`
`m=-4`
Magnification is negative, which means the image is real and inverted.
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संबंधित प्रश्न
An image formed on a screen is three times the size of the object. The object and screen are 80 cm apart when the image is sharply focussed.
State which type of lens is used.
A lens forms an erect, magnified, and virtual image of an object. Name the type of lens.
Analyse the following observation table showing variation of image-distance (v) with object-distance (u) in case of a convex lens and answer the questions that follow without doing any calculations:
| S. No. | Object-Distance u (cm) |
Image-Distance v (cm) |
| 1 | –60 | +12 |
| 2 | –30 | +15 |
| 3 | –20 | +20 |
| 4 | –15 | +30 |
| 5 | –12 | +60 |
| 6 | –9 | +90 |
(a) What is the focal length of the convex lens? State reason for your answer.
(b) For what object-distance (u) is the corresponding image-distance (v) not correct? How did you arrive at this conclusion?
(c) Choose an appropriate scale to draw a ray diagram for the observation at S. No. 4 and find the approximate value of magnification.
While determining the focal length of a convex lens, you try to focus the image of a distant object formed by the lens on the screen. The image formed on the screen, as compared to the object, should be
(A) erect and highly diminished
(B) erect and enlarged
(C) inverted and enlarged
(D) inverted and highly diminished
i. Which type of microscope has the arrangement of lenses shown in the adjoining figure?
ii. Label the figure correctly.
iii. Write the working of this microscope.
iv. Where does this microscope used?
v. Suggest a way to increase the efficiency of this microscope.
State the position of object, position of image, nature of image when: Convex lens is used in observing biological specimens.
In the figure given below L is a convex lens, M is a plane mirror and S is a point source of light. Rays of light from the source S return to their point of origin. Complete the ray diagram to show this. What is the point S called?
Find the odd one out and give its explanation.
Write the name.
The lens used in simple microscope.
Convex lens is also known as ______.
