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 the object. The approximate focal length of the lens is:

An object is kept at a distance of 16 cm from a thin lens and the image formed is real. If the object is kept at a distance of 6 cm from the lens, the image formed is virtual. If the sizes of the images formed are equal, the focal length of the lens will be

An object is kept at a distance of 16 cm from a thin lens and the image formed is real. If the object is kept at a distance of 6 cm from the lens, the image formed is virtual. If the sizes of the images formed are equal, the focal length of the lens will be

An object is kept at a distance of 16 cm from a thin lens and the image formed is real. If the object is kept at a distance of 6 cm from the lens, the image formed is virtual. If the sizes of the images formed are equal, the focal length of the lens will be

When an object is placed at a distance of 15 cm from a convex lens, a real image is formed at a distance of 30 cm. What is the focal length of the lens?

An object is placed 80 cm from converging lens of focal length 25 cm. What is the nature of image?

A object is placed 20 cm from the convex lens, with focal length 40 cm. The image formed is virtual and erect. What will be power of the lens?

When an object is placed 40cm from a diverging lens, its virtual image is formed 20cm from the lens. The focal length and power of lens are

When an object is placed 40cm from a diverging lens, its virtual image is formed 20cm from the lens. The focal length and power of lens are