Question

When is magnification positive or negative?

Answer 1

Hint: In order to answer this question, first we will discuss the conditions when the magnification is positive and negative, we will discuss both the conditions separately. Then we will discuss the magnification.

Complete step-by-step solution:
A convex mirror's magnification is always positive, but a concave mirror's magnification can be either positive or negative. Based on the sign itself, this magnification can reveal information about the image's nature. The picture is actual and inverted if the ratio is negative. The magnification of the spherical mirror is defined as the ratio of the image height to the object height. Because virtual pictures are only erect when they are virtual images, virtual images equal positive magnification. When the picture is reversed, magnification is negative, resulting in a genuine image. When \[m = \dfrac{v}{u}\] is used, however, $m$ is negative when $v$ is negative. And when the image is on the same side of the lens as the object, v is simply negative.
Magnification is the size of an image in relation to the size of the item that created it in optics. The ratio of image length to object length measured in planes perpendicular to the optical axis is known as linear magnification (also known as lateral or transverse magnification). An inverted image has a negative linear magnification value. The factor by which an image grows in size as measured along the optical axis is known as longitudinal magnification. When measured from a particular point in the instrument, such as magnifiers and binoculars, angular magnification is equal to the ratio of the tangents of the angles subtended by an object and its image.
The amount of magnification achievable in an optical system has no theoretical limit, but practical magnification is restricted by the system's resolving power—that is, its capacity to generate recognisable images of objects separated by small angular distances. The diameter is a popular magnification unit in microscopes and telescopes, with magnification in diameters equal to the number of times the object's linear dimensions are enhanced.

Note: If we imagine the lens at the top of a graph, the item is to the left of 0, indicating a negative orientation. A virtual picture would be to the left as well as having a negative distance value. The negatives would cancel out, resulting in a positive magnification.