Final answer:
The size and nature of an image in a mirror change based on the object's distance from the mirror. If the object is moved to a position different from the original 20 cm, such as 5 cm, typically within a concave mirror's focal point, the image becomes virtual, upright, and magnified.
Step-by-step explanation:
The image size for mirrors varies depending on the location of the object in relation to the mirror. When an object is located at different locations from a spherical mirror, like a concave or convex mirror, the size of the image can vary significantly.
Referring to a scenario where a mirror shows an inverted image equal in size to the object at a distance of 20 cm, we can deduce certain characteristics of image formation. When an object is moved closer to the mirror, say at 5 cm, the nature of the image changes. For instance, if we are dealing with a concave mirror, as the object moves within the focal point (closer than the focal length), the image becomes larger, upright, and virtual as opposed to the real and inverted image seen when the object is beyond the focal point.
In the context of multiple images with parallel mirrors, when an object is placed off-center, an infinite number of images can theoretically be produced, with each subsequent image being an inversion of the previous one. Similarly, for plane mirrors, the image is virtual, upright, and the same size as the object, located at the same distance behind the mirror as the object is in front.