Which type of mirror can produce a virtual image?

How can you identify the three types of mirrors without touching them?

How will you identify a convex lens by touching it?

Which of the following always form a virtual image?

Sudha finds out that the sharp image of the window pane of her science laboratory is formed at a distance of $15\, cm$ from the lens. She now tries to focus the building visible to her outside the window instead of the window pane without disturbing the lens. In which direction will she move the screen to obtain a sharp image of the building? What is the approximate focal length of this lens?

$A$ ray of light $AB$ parallel to the principal axis is incident on a convex lens as shown in the figure. Copy the figure.
$(i)$ Draw the refracted ray.
$(ii)$ Name the point through which the refracted ray passes on the principal axis.