Thin lenses — Draw

How is a ray diagram constructed to show the formation of a virtual image by a converging lens?

When the object is placed between the lens and its principal focus, the two construction rays (one parallel to the axis refracting through the focus, one through the centre undeviated) diverge on the far side and never actually meet. Tracing these rays backwards as dashed lines on the same side as the object shows where they appear to meet, forming a virtual, upright, enlarged image.