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प्रश्न
Define the term principal axis of a lens.
उत्तर १
It is the line joining the centers of curvature of the two surfaces of the lens.
उत्तर २
संबंधित प्रश्न
Draw a labelled ray diagram to show how a ray of light is refracted when it passes:
from air into an optically denser medium.
A 1 cm high object is placed at a distance of 2f from a convex lens. What is the height of the image formed?
For what position of an object a real, diminished image is formed by a convex lens?
Fill in the following blank with suitable word:
The image in a convex lens depends upon the distance of the ........... from the lens.
Which of the above two cases illustrates the working of a magnifying glass?
A student did an experiment with a convex lens. He put an object at different distances 25 cm, 30 cm, 40 cm, 60 cm and 120 cm from the lens. In each case he measured the distance of the image from the lens. His results were 100 cm, 24 cm, 60 cm, 30 cm and 40 cm, respectively. Unfortunately his results are written in wrong order.
What would be the image distance if the object distance was 90 cm?
An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens.
What kind of lens can form:
an erect magnified image?
What kind of lens can form:
am erect diminished image?
In the following cases, where must an object be placed in front of a convex lens so that the image formed is upright and enlarged?
Complete the following table:
| Type of lens | Position of object | Nature of image | Size of image |
| Convex | Between optical centre and focus | ||
| Convex | At focus | ||
| Concave | At infinity | ||
| Concave | At any distance |
Out of the five incident rays shown in the figure find the three rays that are obeying the laws of refraction and may be used for locating the position of image formed by a convex lens:
(A) 1, 2 and 3
(B) 2, 3 and 4
(C) 3, 4 and 5
(D) 1, 2 and 4
Point out the difference between a convex lens and a concave lens.
Write the three characteristics of the image formed by a convex lens of focal length 20 cm for the object at distance (i) 10 cm, (ii) 30 cm, (iii) 40 cm, (iv) 60 cm from the lens.
A candle is placed between f and 2f a convex lens. Draw a ray diagram showing the position of the image.
Define the principal focus of a convex lens.
Which of the following statements is true?
Distinguish between:
Concave lens and Convex Lens
Distinguish between Concave lens and Convex Lens.
Distinguish between:
Concave lens and Convex lens
