The distance between an object and a convex lens is changing. It is noticed that the size of the image formed on a screen is decreasing. Is the object moving in a direction towards the lens or away from it?

Academic Physics NCERT Class 7

The size of the image formed by a convex lens is decreased when the distance between the object and the lens is increased. So, the object is moving away from the lens.

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Updated on: 10-Oct-2022

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A 4 cm tall object is placed on the principal axis of a convex lens. The distance of the object from the optical center of the lens is 12 cm and its sharp image is formed at a distance of 24 cm from it on a screen on the other side of the lens. If the object is now moved a little away from the lens, in which way (towards the lens or away from the lens) will he have to move the screen to get a sharp image of the object on it again? How will the magnification of the image be affected?
(a) An object is placed well outside the principal focus of a convex lens. Draw a ray diagram to show how the image is formed, and say whether the image is real or virtual.(b) What is the effect on the size and position of the image of moving the object (i) towards the lens, and (ii) away from the lens?
A real image 2/3rd of the size of an object is formed by a convex lens when the object is at a distance of 12 cm from it. Find the focal length of the lens.
When an object is placed at a distance of 36 cm from a convex lens, an image of the same size as the object is formed. What will be the nature of image formed when the object is placed at a distance of:(a) 10 cm from the lens? (b) 20 cm from the lens?
A converging lens is used to produce an image of an object on a screen. What change is needed for the image to be formed nearer to the lens?(a) increase the focal length of the lens (b) insert a perging lens between the lens and the screen(c) increase the distance of the object from the lens (d) move the object closer to the lens
An image formed by a lens is erect. Such an image could be formed by a$(a)$. convex lens provided the image is smaller than object.$(b)$. concave lens provided the image is smaller than object.$(c)$. concave lens provided the image is larger than object.$(d)$. concave lens provided the image is of the same size.
If an object is at a considerable distance (or infinity) in front of a convex lens, where is the image formed?
lt was observed that when the distance between an object and a lens decreases, the size of the image increases. What is the nature of this lens? If you keep on decreasing the distance between the object and the lens, will you still able to obtain the image on the screen? Explain.
If an object is placed at the focus of a convex lens, where is the image formed?
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.(a) State which type of lens is used.(b) Calculate focal length of the lens.
If 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?
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.
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.(a) What is the distance between the object and the lens?(b) Where should the object be placed if the image is to form at infinity?
A 1 cm high object is placed at a distance of 2f from a convex lens. What is the height of the image formed?
An object kept \( 60 \mathrm{~cm} \) from a lens gives a virtual image \( 20 \mathrm{~cm} \) in front of the lens. What is the focal length of the lens? Is it a converging lens or diverging lens?

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