An object is placed 50 cm from a lens produces a virtual image at a distance of 10 cm in front of the lens. Draw a diagram to show the formation of image and calculate the focal length of the lens.
Distance of object from the mirror u=−50 cm
Distance of image from the mirror v=−10 cm
For lens, we know
1f=1v−1u
1f=1−10−1−50
f=−12.5cm
It is a concave lens.