In practical optics, a convex mirror is generally chosen for which common application because it provides a wide field of view and an upright, diminished image?

Introduction / Context:
Mirrors with different shapes, such as concave and convex mirrors, are used for different purposes depending on how they form images. Convex mirrors curve outward and have special image forming properties that are particularly useful in some everyday applications. This general knowledge question asks where convex mirrors are commonly used and tests whether you can connect their optical behaviour with a practical device you see daily on vehicles.

Given Data / Assumptions:
- The mirror under consideration is convex and curves outward.- A convex mirror produces virtual, upright, and diminished images located behind the mirror.- A wide field of view is the main advantage in the chosen application.

Concept / Approach:
Convex mirrors diverge light rays and make objects appear smaller than they really are, which allows them to show a larger region in a single view. This wide field of view is important for safety in driving, as the driver needs to see vehicles approaching from behind and from adjacent lanes. Therefore, convex mirrors are widely used as rear view mirrors on cars, buses, and motorcycles. Concave mirrors, on the other hand, converge light and are used in solar cookers, headlights, and some medical instruments, where focusing light is important rather than increasing field of view.

Step-by-Step Solution:
1. Recall that convex mirrors always form virtual, erect, and diminished images, regardless of object position.2. Remember that these mirrors allow a larger field of view because they capture light from a wider region and form smaller images on the mirror surface.3. Identify the real world application where seeing a wide area behind and to the side is crucial, which is the rear view mirror in vehicles.4. Recognise that solar cookers require concentration of sunlight at a point, which is achieved with concave, not convex, mirrors.5. Note that headlights and some medical viewing instruments also use concave mirrors to focus or direct light strongly.6. Therefore, the application best suited for a convex mirror in the given options is the rear view mirror.

Verification / Alternative check:
You can verify this simply by observing the writing on many vehicle mirrors, which often say objects in the mirror are closer than they appear. This is a characteristic of convex mirrors producing reduced images. Automobile engineering diagrams and driving manuals explicitly describe using convex mirrors for side and sometimes centre rear view mirrors to provide a wide angle view. This practical confirmation supports the theoretical reasoning about convex mirrors and their common application.

Why Other Options Are Wrong:
- Solar cookers: They use concave mirrors to concentrate sunlight at a focal point for heating and cooking.- Ophthalmoscope: This medical instrument commonly uses a concave mirror with a small hole to focus light into the eye.- Reflector for a headlight: Headlights use concave mirrors or reflectors to direct parallel beams of light down the road.

Common Pitfalls:
Some students may assume that any mirror in an optical device can be convex without considering the required function. Distinguishing between applications that need focusing (concave) and those that need wide field vision (convex) will help you choose the correct mirror type. A good memory aid is to remember convex for viewing behind in vehicles and concave for concentrating light in devices like headlights and solar cookers.

Final Answer:
A convex mirror is generally used as a rear view mirror in vehicles.