Question

how image will form in concave mirror when the object is at point f​

Answer 1

$\huge\mathfrak\blue{Answer:}$

When objects are placed at different positions infront of a concave mirror, images are also formed at different places.

When the object is placed in front of the concave mirror at F ( Focus) :

The image will be formed at infinity.

Nature of the image would be Real, infinitely large and inverted.

I wil provide the image of this in attachment.