If a magnification of, $-$1 is to be obtained by using a converging lens of focal length 12 cm, then the object must be placed:(a) within 12 cm (b) at 24 cm (c) at 6 cm (d) beyond 24 cm
(b) at 24 cm
Explanation
Since, the magnification of the image is negative, it means the nature of the image is real and inverted. Also, size of the image is equal to 1, which implies that the size of the image is equal to the size of the object.
Thus, the image of this nature and size is formed when the object is placed at $2f$ of the convex lens.
Here, the focal length $f$ is 12 cm, then the $2f$ will be 24 cm $(2\times {12})$, so the object should be placed at 24 cm.
Image is posted for reference only
Related Articles
- In order to obtain a magnification of, $-$0.75 with a convex lens of focal length 8 cm, the object should be placed:(a) at less than 8 cm (b) between 8 cm and 16 cm(c) beyond 16 cm (d) at 16 cm
- 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
- To obtain a magnification of, $-$2 with a convex lens of focal length 10 cm, the object should be placed:(a) between 5 cm and 10 cm (b) between 10 cm and 20 cm(c) at 20 cm (d) beyond 20 cm
- At what distance from a converging lens of focal length 12 cm must an object be placed in order that an image of magnification 1 will be produced?
- In order to obtain a magnification of, −1.5 with a concave mirror of focal length 16 cm, the object will have to be placed at a distance(a) between 6 cm and 16 cm (b) between 32 cm and 16 cm(c) between 48 cm and 32 cm (d) beyond 64 cm
- A lens of focal length 12 cm forms an erect image three times the size of the object. The distance between the object and image is:(a) 8 cm (b) 16 cm (c) 24 cm (d) 36 cm
- If a magnification of, –1 (minus 1) is obtained by using a converging lens, then the object has to be placed:(a) within $f$ (b) at $2f$(c) beyond $2f$ (d) at infinity
- A convex lens of focal length 10 cm is placed in contact with a concave lens of focal length 20 cm. The focal length of this combination of lenses will be:(a) +10 cm (b) +20 cm (c) −10 cm (d) −20 cm
- A convex lens of focal length 8 cm forms a real image of the same size as the object. The distance between object and its image will be:(a) 8 cm (b) 16 cm (c) 24 cm (d) 32 cm
- The power of a lens is +2.0D. Its focal length should be :(a) 100 cm (b) 50 cm (c) 25 cm (d) 40 cm
- A concave lens produces an image 20 cm from the lens of an object placed 30 cm from the lens. The focal length of the lens is:(a) 50 cm (b) 40 cm (c) 60 cm (d) 30 cm
- If an object is placed 21 cm from a converging lens, the image formed is slightly smaller than the object. If the object is placed 19 cm from the lens, the image formed is slightly larger than object. The approximate focal length of the lens is:(a) 5 cm (b) 10 cm (c) 18 cm (d) 20 cm
- An object is placed at a distance of 4 cm from a concave lens of focal length 12 cm. Fine the position and nature of the image.
- A convex lens has a focal length of 10 cm. At which of the following position should an object be placed so that this convex lens may act as a magnifying glass? (a) 15 cm (b) 7 cm (c) 20 cm (d) 25 cm
- At what distance should an object be placed from a convex lens of focal length 18 cm to obtain an image at 24 cm from it on the other side. What will be the magnification produced in this case?
Kickstart Your Career
Get certified by completing the course
Get Started