When a concave mirror forms an image on a screen placed in front of it, what type of image is produced?

Introduction / Context:
Image formation by mirrors and lenses is a standard topic in school physics. A key idea is the distinction between real and virtual images. This question specifically mentions an image formed by a concave mirror that appears on a screen. Understanding what this implies about the nature of the image is important for optics based questions.

Given Data / Assumptions:
- The reflecting surface is a concave mirror.- An image of an object has been obtained on a physical screen.- We assume that the usual rules of ray optics apply.

Concept / Approach:
By definition, a real image is one in which light rays actually converge to a point in space, so the image can be obtained on a screen. A virtual image appears to come from a point from which light seems to diverge, and it cannot be captured on a screen. Concave mirrors are capable of forming both real and virtual images depending on the object position, but whenever the image can be projected onto a screen, it must be a real image, and it is inverted with respect to the object.

Step-by-Step Solution:
1. Recall the definition: a real image is formed where light rays actually meet and can be obtained on a screen.2. Recall that a virtual image is formed where rays only appear to diverge from a point and cannot be projected on a screen.3. The question clearly states that the image is formed on a screen, which directly implies it is real.4. Concave mirrors can form real, inverted images when the object is placed beyond the focal length.5. Therefore, the correct description is that the image is a real image.

Verification / Alternative check:
In the laboratory you can place a concave mirror on a bench, keep an object like a candle beyond the centre of curvature, and adjust a screen until a sharp inverted image appears. This experiment shows that the image produced can be caught on a screen and is therefore real. In contrast, the enlarged upright face image you see in a concave shaving mirror cannot be projected onto a screen and is virtual.

Why Other Options Are Wrong:
- Virtual image: A virtual image cannot be projected onto a screen, so it contradicts the given condition.- Erect image: Real images formed by a concave mirror for standard object positions are inverted, not erect.- Magnified upright image: This describes a virtual image formed when the object is within the focal length, not an image that appears on a screen.

Common Pitfalls:
Students sometimes think that any clear image is virtual simply because it is visible. Always remember the operational test: if you can catch the image on a screen, it is real. The terms erect and inverted describe orientation, whereas real and virtual describe how the rays behave and whether a screen can capture the image.

Final Answer:
An image formed by a concave mirror on a screen is a real image.