What is the angle of incidence for a light ray incident on a glass slab such that it does not undergo refraction (in $^{\circ}$)?

$A$ child is standing in front of a magic mirror. She finds the image of her head bigger, the middle portion of her body of the same size, and that of the legs smaller. What is the order of combinations for the magic mirror from the top?

The figure below shows the refraction and emergence of a ray of light incident on a rectangular glass slab. Copy the diagram and mark the lateral displacement of the incident ray. Name the two factors on which the lateral displacement depends.

$A$ beam of light incident on a plane mirror forms a real image on reflection. The incident beam is

What is a lens?

Draw ray diagrams showing the image formation by a concave lens when an object is placed:
$(a)$ at the focus of the lens
$(b)$ between focus and twice the focal length of the lens
$(c)$ beyond twice the focal length of the lens