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प्रश्न
In order to obtain a real image twice the size of the object with a convex lens of focal length 15 cm, the object distance should be:
(a) more than 5 cm but less than 10 cm
(b) more than 10 cm but less than 15 cm
(c) more than 15 cm but less than 30 cm
(d) more than 30 cm but less than 60 cm
उत्तर
More than 15 cm but less than 30 cm
For an object placed between F and 2F of a convex lens, the image formed is real and enlarged.
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संबंधित प्रश्न
To find the image-distance for varying object-distances in case of a convex lens, a student obtains on a screen a sharp image of a bright object placed very far from the lens. After that he gradually moves the object towards the lens and each time focuses its image of the screen.
(a) In which direction – towards or away from the lens, does he move the screen to focus the object?
(b) What happens to the size of image – does it increase or decrease?
(c) What happen when he moves the object very close to the lens?
Study the given ray diagrams and select the correct statement from the following:
(A) Device X is a concave mirror and device Y is a convex lens, whose focal lengths are 20 cm and 25 cm respectively.
(B) Device X is a convex lens and device Y is a concave mirror, whose focal lengths are 10 cm and 25 cm respectively.
(C) Device X is a concave lens and device Y is a convex mirror, whose focal lengths are 20 cm and 25 cm respectively.
(D) Device X is a convex lens and device Y is a concave mirror, whose focal lengths are 20 cm and 25 cm respectively.
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.
An object 2 cm tall is placed on the axis of a convex lens of focal length 5 cm at a distance of 10 m from the optical centre of the lens. Find the nature, position and size of the image formed. Which case of image formation by convex lenses is illustrated by this example?
If the object is moved to a point only 3 cm away from the lens, what is the new position, height and nature of the image?
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:
0.50 m
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
If an object is placed in front of a convex lens beyond 2F1, then what will be the position, relative size, and nature of an image which is formed? Explain with a ray diagram.
Differentiate convex lens and concave lens.
- In which type of microscope do you find the lens arrangement as shown in the following diagram?
- Write about the working and the use of this microscope.
