Final answer:
The size of an image changes when a light bulb is moved along the central axis of a concave mirror and depends on its distance from the focal point or center of curvature of the mirror.
Step-by-step explanation:
The student's question pertains to the behavior of a light bulb's image when moved along the central axis of a concave mirror. According to the provided scenarios, the light bulb could be at the focal point or the center of curvature of one or two mirrors. Regardless of the specific position mentioned in each scenario, when the light bulb is moved along the central axis, the size of the image and its position will vary based on the bulb's distance from the mirror's focal point or center of curvature. For example, when the light source is at the focal point of a concave mirror, no real image is formed because the reflected rays are parallel. However, if the source is at the center of curvature, the image produced will be real, inverted, and of the same size as the object (the bulb).
For a lens, if the light source is inside the focal length, the image will appear on the same side as the object and will be magnified. If the object is beyond one focal length, a real image is formed on the opposite side. Ray tracing helps predict the exact image location and size. So, the consistency in behavior of light based on ray optics is what remains true regardless of the position of the light source in these scenarios.