Q. Consider the following:

1. Convex lens
2. Concave lens
3. Concave mirror
4. Convex mirror
5. Plane mirror

Which of the above can form a real image of a real object?
Answer: Only 1 and 3
Notes: Only convex lenses and concave mirrors can form a real image of a real object when the object is suitably placed. Concave lenses, convex mirrors, and plane mirrors can only form virtual images of real objects under all cases, thus cannot produce real images as per the given conditions.