Question

In an experiment to determine the focal length of a convex lens, a student obtained a sharp image of a grill of a window on a screen. To obtain the sharp image of a distant building instead of grill, on which direction should he move the lens?

Answer 1

I think he should keep the mirror at infinity so that the image will be sharp

Answer 2

He should move the lens away from the window to obtain a sharp image at the focus of the lens.