The correct option is (b) 2 and 3 only.
Explanation
To form an image on a physical screen, such as a sheet of paper, the optical device must produce a real image. A real image is formed when light rays originating from an object actually converge (meet) at a specific point after reflection or refraction. Virtual images, formed by diverging rays that appear to meet behind the device, cannot be projected onto a screen. Since the Sun is an object at infinity, the incident light rays are parallel.
Device Analysis:
- 1. Plane Mirror (Incorrect): A plane mirror always forms a virtual, erect, and laterally inverted image located behind the mirror. The reflected rays diverge and do not actually meet; thus, the image cannot be captured on a sheet of paper.
- 2. Concave Mirror (Correct): A concave mirror is a converging mirror. Parallel light rays from the Sun reflect off the surface and converge at the principal focus in front of the mirror. This forms a real, inverted, and point-sized image on a screen placed at the focal point.
- 3. Convex Lens (Correct): A convex lens is a converging lens. Parallel light rays passing through the lens refract and converge at the principal focus on the opposite side. This forms a real, inverted, and point-sized image that can be projected onto a sheet of paper.
- 4. Concave Lens (Incorrect): A concave lens is a diverging lens. Parallel light rays passing through it spread out (diverge). These rays appear to originate from a virtual focus on the same side as the source. Consequently, it forms a virtual, erect, and diminished image which cannot be projected on a screen.
Key Takeaway:
Only converging optical devices (Concave Mirrors and Convex Lenses) can form real images. Diverging devices (Concave Lenses and Convex Mirrors) and Plane Mirrors form virtual images.