To solve the problem, we need to identify the position of the object for which a concave mirror forms a virtual image.
1. Properties of a Concave Mirror:
A concave mirror usually forms real and inverted images, but under certain conditions, it forms a virtual image.
This occurs only when the object is placed very close to the mirror.
2. Condition for Virtual Image Formation:
A concave mirror forms a virtual, erect, and magnified image when the object is placed between the pole (P) and the focus (F).
Final Answer:
A virtual image is formed when the object is placed between the pole (P) and F.