Question

The rear view mirror in an automobile often has a warning that reads, "OBJECTS IN THE MIRROR ARE CLOSER THAN THEY APPEAR". Which of the options is/are the correct implication(s) of this warning?

• A. The mirror is magnifying objects to make them appear larger.
• B. The mirror is showing objects smaller than their actual size.
• C. The mirror is showing objects in the same size as they appear.
• D. The mirror is showing a wider view of the area.

Hint:

Remember the three common types of mirrors: Plane (same size image, used for driver's mirror), Convex (smaller image, wider view, used for passenger's mirror), and Concave (can magnify, used for shaving or makeup mirrors). Associating each type with its common use case can help you remember its properties.

Answer 1

The Correct Option is B, D

Step 1: Understanding the Concept:
The warning label is typically found on the passenger-side mirror of cars. These mirrors are not flat (plane mirrors) but are curved outwards. This type of mirror is called a convex mirror. We need to understand the optical properties of convex mirrors.
Step 2: Key Formula or Approach:
Properties of a Convex Mirror: 1. It diverges light rays that strike its surface. 2. It always forms an image that is virtual, erect (upright), and diminished (smaller than the object). 3. It has a wider field of view compared to a plane mirror of the same size.
Step 3: Detailed Explanation:
Let's connect these properties to the warning and the options:
The Warning: "OBJECTS... ARE CLOSER THAN THEY APPEAR". Our brain judges distance based on the apparent size of familiar objects. Because a convex mirror makes objects look smaller (diminished), our brain interprets them as being farther away than they actually are. The warning is there to correct for this perceptual illusion.
Now let's evaluate the options:
A. The mirror is magnifying objects... This is false. Magnification would make objects appear larger and closer. Convex mirrors do the opposite.
B. The mirror is showing objects smaller than their actual size. This is true. This is the direct optical reason for the perceptual effect described in the warning.
C. The mirror is showing objects in the same size... This is false. This is the property of a flat (plane) mirror, which is usually the driver-side mirror.
D. The mirror is showing a wider view of the area. This is true. This is the very reason a convex mirror is used in this application. Its ability to capture a wider field of view helps to reduce the driver's blind spots, which is a significant safety benefit that outweighs the downside of distance distortion.
Step 4: Final Answer:
The warning is a direct consequence of the fact that the mirror shows objects smaller (B). The reason for using such a mirror is that it provides a wider view (D). Both are correct implications related to the warning.