Question

For a point object, which of the following always produces virtual image in air?

• A. Plano-Convex lens
• B. Convex mirror
• C. Biconvex lens
• D. Concave mirror

Answer 1

The Correct Option is B

• Plano-Convex lens: Produces real images for objects outside focal length; produces virtual images only when object is inside focal length. Thus, not always virtual. 
• Convex mirror: Always forms virtual, erect, and diminished images, irrespective of object distance. Therefore, always produces virtual images.
• Biconvex lens: Produces real images for objects beyond focal length; virtual images only when object is within focal length. Thus, not always virtual.
• Concave mirror: Can produce both real and virtual images depending on the object position. Thus, not always virtual.

Final Conclusion:
Among the given options, only a Convex mirror always produces virtual images.

Answer 2

A convex mirror always produces a virtual, erect, and diminished image for any object placed in front of it. This is because the reflected rays diverge after reflection, and the virtual image is formed where the extensions of these rays meet behind the mirror.

In contrast:

- A plano-convex lens can form both real and virtual images depending on the object distance.
- A biconvex lens can also form both real and virtual images, again depending on the object distance.
- A concave mirror typically forms a real image for objects beyond the focal point, but for objects within the focal length, it forms a virtual image.

Therefore, the convex mirror is the only option that always produces a virtual image in air.