Question

A full-length image of a distant tall building can definitely be seen by using:

• A. A concave mirror
• B. A convex mirror
• C. A plane mirror
• D. Both concave as well as plane mirror

Answer 1

The correct option is B

A convex mirror

Correct Option: Option B

1. A convex mirror is a curved mirror such that the surface that bulges out is reflective.
2. Convex mirrors always form virtual, upright, and smaller images.
3. So by using a convex mirror, a smaller and upright image of the building can be obtained.
4. Given below is an illustration of an image formed by a convex mirror, where $AB$ is the building and $A\text{'}B\text{'}$ is its image.

Incorrect options:

Option A

1. The image formed by a concave mirror is smaller and inverted. It forms an erect, magnified image of the object when the object is placed close to the pole of the mirror.
2. So, it cannot be used to capture the image of a tall building. Thus, this option is incorrect.

Option C

1. The image formed by a plane mirror is of the same size.
2. So, it can only produce the image of the building if the mirror is at least the same size as the building or even bigger, but this is not feasible. Thus, this option is incorrect.

Option D

Neither a concave mirror nor a plane mirror can be used to capture the full length of the building. Thus, this option is incorrect.

Hence, option B is correct.