A diminished image is an image that appears smaller than the original object it represents.
Understanding Diminished Images
In optics, the size of an image formed by a lens or mirror can differ significantly from the size of the actual object. When discussing image formation, we categorize images based on their relative size compared to the object:
- Enlarged Image: The image is larger than the object.
- Diminished Image: The image is smaller than the object.
- Same Size Image: The image is the same size as the object.
According to the provided reference, "If the size of an image is smaller than that of the object then the image is called a diminished image." This fundamental definition highlights the key characteristic of a diminished image: its reduced scale relative to the source object.
Key Characteristics
- Relative Size: The defining feature is that the image's dimensions (height, width) are less than the corresponding dimensions of the object.
- Formation: Diminished images are formed under specific conditions depending on the type of lens or mirror used and the object's position. For example:
- Convex mirrors always form diminished, virtual, and erect images.
- Convex lenses can form diminished images when the object is placed beyond twice the focal length (2F). These images are typically real and inverted.
- Concave lenses always form diminished, virtual, and erect images.
Examples and Practical Applications
Diminished images are common in everyday life and various optical instruments:
- Rearview Mirrors in Cars: These are typically convex mirrors that provide a wider field of view by forming small, diminished images of objects behind the vehicle. This helps drivers see more traffic, although the diminished size makes objects appear farther away than they are.
- Camera Lenses: When photographing distant objects, the lens often forms a diminished image on the camera's sensor or film.
- Eyes: The lens in the human eye forms a diminished, inverted image on the retina. The brain then interprets this image correctly.
- Optical Instruments: Telescopes use multiple lenses or mirrors to form images, and intermediate or final images can be diminished depending on the design.
Understanding the formation of diminished images is crucial in fields like photography, astronomy, and the design of optical systems.
