Concave mirror
Explanation
The selection of a mirror for specific optical applications depends on the nature of the image formed specifically regarding magnification and orientation. For dental examinations, the requirement is to obtain an erect and magnified image of the teeth to inspect cavities and minute details effectively.
Option Analysis
- Convex mirror is Incorrect: A convex mirror always forms a virtual, erect, and diminished (smaller than the object) image, regardless of the object's distance. While it offers a wide field of view (useful for rear-view mirrors in vehicles), it cannot provide the magnification necessary for medical examination.
- Plane mirror is Incorrect: A plane mirror forms a virtual and erect image that is of the same size as the object. It does not provide magnification.
- Concave mirror is Correct: A concave mirror acts as a converging mirror. When an object is placed within the mirror's focal length (between the pole and the principal focus), it produces a virtual, erect, and magnified image. This property allows dentists to see an enlarged view of the tooth structure.
- Spherical lens is Incorrect: While spherical lenses can magnify images, the question specifically asks for a "mirror." Mirrors operate on the principle of reflection, whereas lenses operate on refraction.
Key Takeaway: Concave mirrors are utilized in applications requiring the magnification of objects placed close to the surface, such as in dentist mirrors, shaving mirrors, and makeup mirrors.