Final answer:
A real image can be directly observed without needing to project it onto a screen; it exists when light rays actually converge in real space. Virtual images cannot be projected onto a screen but can be photographed, as they appear to the eye or camera from a point behind the mirror or lens.
Step-by-step explanation:
Is it necessary to project a real image onto a screen to see it? The answer is 'b. No, real images can be seen directly without projection.' Real images are formed when light rays emanating from an object converge at a point in space. This is the case with lenses in cameras and in the human eye, where the lens focuses light to form an image on the retina.
A virtual image, on the other hand, is formed by rays that appear to come from a point behind the mirror or lens. You can see virtual images, as they are what you observe when looking into flat mirrors (like your bathroom mirror). These images are perceived by the eye but cannot be projected onto a screen because the rays don't actually converge in real space.
To answer a related question, virtual images cannot be projected onto a screen with additional lenses or mirrors; however, you can photograph a virtual image because the camera lens or your eye can focus the light coming from the apparent position of the virtual image.
In conclusion, a real image does not need to be projected onto a screen for it to exist. It is necessary only when you want to display the image on a surface, as in the case of a projector or a camera film.