question_answer

A point object is placed at a focus of a double concave lens. The image will be

A)  real and at infinity

B)  virtual and at infinity

C)  virtual and located between the object and lens  

D)  none of the above

Correct Answer: C

Solution :

 In a concave lens, the maximum image distance for a real object can be equal to focal length. When the object is at infinity, the virtual image is formed at focus. When the object is anywhere between infinity and optical centre, the virtual image is formed between focus and optical centre. So, the correct option is [c]. Concave lens can form a real image of the object at infinity if the object is virtual and is at focus as shown in figure.