Question

An object is placed at a principle focus of a convex mirror. The image will be at?
A.Centre of curvature
B.Principle focus
C.Infinity
D.No image will be formed

Answer 1

We know that for a convex mirror the focus and the center of curvature are both imaginary points. If the focus is imaginary no object can be placed there, so in this case, no image will be formed

Complete answer:
The Convex Mirror is a curved mirror in which the reflective surface bulges towards the source of light (and the coating of reflecting substances is in the bulge facing away from the source of light). This bulging out surface reflects outward light and is not used for light-concentrating. As the focal point (F) and the center of curvature (2F) are imaginary points in the mirror that cannot be reached, these mirrors form a virtual image. This results in the creation of images that, as the picture is within the mirror, cannot be projected on a screen.

Since the principal focus is an imaginary point, there is no way we can place a real object there. So, since the object cannot be placed at the principal focus (an imaginary point) an image will also not be formed in this case.

Hence, option D is the correct choice.

Note:
In the solution, we discussed that the convex mirror cannot form a real image for a real object. This does not mean that convex mirrors cannot form real images, they do form real images but only if the object is virtual. In simple words for virtual objects, convex mirrors can form a real image.