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प्रश्न
A magnifying lens has a focal length of 100 mm. An object whose size is 16 mm is placed at some distance from the lens so that an image is formed at a distance of 25 cm in front of the lens.
Where should the object be placed if the image is to form at infinity?
उत्तर
The object should be placed at the focus for the image to be formed at infinity.
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संबंधित प्रश्न
The image formed by a concave mirror is real, inverted and of the same size as the object. The position of the object must then be:
(a) at the focus
(b) between the centre of curvature and focus
(c) at the centre of curvature
(d) beyond the centre of curvature
Fill in the following blank with suitable word:
If the magnification has a minus sign, than the image is ......... and .......
A virtual, erect and magnified image of an object is to be obtained with a convex lens. For this purpose,the object should be placed:
(a) between 2F and infinity
(b) between F and optical centre
(c) between F and 2F
(d) at F
A small object is so placed in front of a convex lens of 5 cm focal length that a virtual image is formed at a distance of 25 cm. Find the magnification.
An object is placed at a distance of 100 cm from a converging lens of focal length 40 cm.
(i) What is the nature of image?
(ii) What is the position of image?
An object placed 4 cm in front of a converging lens produces a real image 12 cm from the lens.
(a) What is the magnification of the image?
(b) What is the focal length of the lens?
(c) Draw a ray diagram to show the formation of image. Mark clearly F and 2F in the diagram.
A convex lens produces a magnification of + 5. The object is placed:
(a) at focus
(b) between f and 2f
(c) at less than f
(d) beyond 2f
The magnification produced by a spherical lens and a spherical mirror is + 2.0.
(a) The lens and mirror are both concave
(b) The lens and mirror are both convex
(c) The lens is convex but the mirror is concave
(d) The lens is concave but the mirror is convex
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.
Calculate focal length of the lens.
What is the nature of the image formed by a concave mirror if the magnification produced by the mirror is +4?
