Image Formed by Concave lens

This construction shows the ray diagram that demonstrates the image formed by a concave lens. The red arrow represents the object and the blue arrow represents the image formed. Click and drag the point at the tail of the red arrow (object) to see how the image changes in response to the position of the object along the principle axis.
1. Is the image formed real or virtual? 2. Does concave lens produce real image? 3. Describe the changes in the image when the object moves along the principle axis. Constructed by Ooi Soo Huat, SMK CHE TOM, KEDAH, MALAYSIA