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प्रश्न
For which position of the object does a convex lens form a virtual and erect image? Explain with the help of a ray diagram.
उत्तर
When an object is placed between the focus and the optical centre of a convex lens, a virtual and erect image of the object is formed.
When the object is placed between the focus F1 and optical centre O:
In this case, the image is formed on the same side as the object. This image is virtual, erect, and very large in size. It is formed behind 2F1.
P’Q’ is the image.
PQ is the object.
F2 is the focus on the other side of the lens.
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संबंधित प्रश्न
A student places a candle flame at a distance of about 60 cm from a convex lens of focal length 10 cm and focuses the image of the flame on a screen. After that he gradually moves the flame towards the lens and each time focuses the image on the screen.
(a) In which direction-toward or away from the lens, does he move the screen to focus the image?
(b) How does the size of the image change?
(c) How does the intensity of the image change as the flame moves towards the lens?
(d) Approximately for what distance between the flame and the lens, the image formed on the screen is inverted and of the same size?
An object is placed at a distance of 15 cm from a concave lens of focal length 30 cm. List four characteristics (nature, position, etc.) of the image formed by the lens.
A beam of light travelling in a rectangular glass slab emerges into air. Draw a ray-diagram indicating the change in its path.
f the image formed by a convex lens is of the same size as that of the object, what is the position of the image with respect to the lens?
State any two uses of convex lenses.
State whether convex lens has a real focus or a virtual focus.
Name one simple optical instrument in which the above arrangement of convex lens is used.
Calculate the focal length of a convex lens which produces a virtual image at a distance of 50 cm of an object placed 20 cm in front of it.
In figure , name the ray which represents the correct path of light while emerging out through
a glass block.
A teacher sets up the stand carrying a convex lens of focal length 15 cm at 42.7 cm mark on the optical bench. He asks four students A, B, C and D to suggest the position of screen on the optical bench so that a distinct image of a distant tree is obtained almost immediately on it. The positions suggested by the students were as
A. 12.7 cm
B. 29.7 cm
C. 57.7 cm
D. 72.7 cm
The correct position of the screen was suggested by
(a) A
(b) B
(c) C
(d) D
