When is the virtual image formed?
Correct answer (a)
Virtual image is formed when the rays of light after reflection or refraction appear to meet at a point.If light rays, after reflection or refraction, actually meets at a point then real image is formed and if they appears to meet virtual image is formed.
For example if a ray of light from the object, parallel to the principal axis, when passes through a concave lens seem to be coming out of its focus but do not actually meet.Hence a virtual image is formed.