A ray of light is going towards the focus of a concave lens. draw a ray diagram to show the path of this ray of light after refraction through the lens.

 A ray of light going towards the focus of a concave lens will become parallel to the principal axis after refraction.

Explanation

According to the 3rd rule for obtaining images formed by concave lens, "A ray of light going towards the focus of a concave lens, becomes parallel to its principal axis after refraction through the lens".

It is the reverse case of the 1st rule, which states that "A ray of light which is parallel to the principal axis of a concave lens, appears to be coming from its focus after refraction through the lens".