Why Do We Use a Minus Sign in the Formula of Magnification of a Mirror (m = -v/u)?

The formula for the magnification (m) produced by a mirror is m = -v/u, where v is the image distance and u is the object distance from the mirror. The minus sign is crucial because it indicates the orientation of the image relative to the object.

A negative magnification means the image is inverted (upside down) compared to the object and is real, while a positive magnification indicates an upright, virtual image. The sign convention helps in distinguishing between real and virtual images and is essential for accurate calculations in optics.

Real-World Example

In a concave mirror, if an object is placed beyond the focal point, the image formed is real, inverted, and the magnification is negative.

Actionable Insights

• Always pay attention to sign conventions in physics formulas to interpret results correctly.
• Understanding image orientation is vital in designing optical devices like cameras and telescopes.