What is meant by a negative magnification for a mirror? Under what conditions does it occur? a. It means the image and object are on opposite sides of a concave mirror. It occurs when the object distance is greater than the focal length. b. It means the image and object are on the same side of a concave mirror. This occurs when the object distance is greater than the focal length. c. It means the image and object are on the same side of a concave mirror. This occurs when the object distance is less than the focal length. d. It means the image and object are on opposite sides of a concave mirror. This occurs when the object distance is less than the focal length.
The Correct Answer and Explanation is:
The correct answer is:
a. It means the image and object are on opposite sides of a concave mirror. It occurs when the object distance is greater than the focal length.
Explanation:
Magnification in mirror systems refers to the ratio of the height of the image to the height of the object. It is represented mathematically as:
Magnification (M) = – (Image distance) / (Object distance)
The negative sign in the formula indicates that when the magnification is negative, the image formed is inverted compared to the object.
For concave mirrors, the nature and position of the image depend on the position of the object relative to the mirror’s focal point:
- When the object is placed beyond the focal point (object distance greater than focal length), the concave mirror forms a real and inverted image. In this case, the image appears on the opposite side of the mirror relative to the object, and the magnification is negative. The negative magnification tells us the image is inverted, and the real image is formed in front of the mirror’s reflecting surface, opposite to the object’s position.
- When the object is placed between the focal point and the mirror (object distance less than the focal length), the mirror forms a virtual, upright, and enlarged image on the same side as the object. In such cases, the magnification is positive.
Thus, a negative magnification occurs for concave mirrors when the object is placed beyond the focal length, resulting in an inverted, real image located on the side opposite to the object.
This behavior is important in applications like telescopes, shaving mirrors, and other optical instruments where real and inverted images are required for accurate reflection or projection.
