BlogNCERTMagnification -The Detailed Study

Magnification -The Detailed Study


Spherical mirrors are mirrors having curved surfaces that can be painted on one in all their sides. Spherical mirrors wherein inward surfaces are painted are called convex mirrors even as the mirrors wherein outward surfaces are painted are called concave mirrors.

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    Concave mirrors also are called converging mirrors because the rays converge after falling at the concave mirror even as convex mirrors are called diverging mirrors because the rays diverge after falling at the convex mirror.

    Magnification, in optics, is the size of an image relative to the scale of the object making it. Linear (sometimes known as lateral or transverse) magnification refers to the ratio of image length to object length measured in planes that are perpendicular to the optical axis. A negative value of linear magnification denotes an associated inverted image. Longitudinal magnification denotes the issue that an image will increase in size, as measured on the optical axis. Angular magnification is adequate to the ratio of the tangents of the angles subtended by an object and its image once measured from a given purpose in the instrument, like magnifiers and binoculars.

    Spherical Mirror Formula

    The Mirror method explains how object distance (u) and image distance (v) are associated with the focal duration around the mirror. The object distance is the gap of the object from the pole of the mirror; denoted through the letter u. The image distance is the gap of the image from the pole of the mirror and its miles denoted through the letter v. And the focal length is the gap of the most important focus from the pole of the mirror. The expression which offers the relation among those 3 portions is known as the mirror formula that’s given as:

    1/v + 1/u = 1/f

    Objects can be positioned in any position on any spherical mirror according to the mirror formula.

    Magnification Equation

    Magnification is the increase within the image size made by spherical mirrors with relevance to the thin size. it’s the magnitude relation of the peak of the image to the height of the object and is denoted as m. The magnification, m produced by a spherical mirror may be expressed as:


    In this case, h is the height of the image, and h’ is the height of the object.

    In addition to image distance and object distance, magnification is proportional to both.

    m = v/u

    As the object is often on top of the principal axis, the peak of the object is always positive. However, a symbol for image height could vary per the sort of image formed. The peak of virtual images ought to be taken positively whereas the height of real images should be taken negatively.

    Mirror Magnification

    Magnification helps us in judging the dimensions of the image formed compared to the object. It tells us whether or not the image formed is magnified, diminished, up to the object once the object is placed at completely different positions on the principal axis. In the case of a mirror, real images are formed ahead of the mirror and virtual images are formed behind the mirror.

    From the formulas mentioned above, we will see that when the magnification is positive, meaning the image distance is positive or the image is created behind the mirror. therefore it’s virtual. And once the magnification is negative, meaning the image distance is negative or the image is created ahead of the mirror. therefore it’s real. In this way, magnification helps us in judging images for being virtual or real.

    Some points to recollect are,

    The positive magnitude of magnification indicates virtual and erect images.

    The negative magnitude of magnification indicates a true and inverted image

    Uses of Magnification

    A preciseness magnifier serves the role of an easy magnifier however holds multiple components to erase aberrations and yield a sharp image.

    A water drop acts as a simple magnifier that magnifies the item behind it. The water forms spherical droplets thanks to the influence of surface tension. Once the droplet is in touch with an object, a spherical form is distorted but capable of forming an image.

    For better understanding take look at the given example

    Question: What is the magnification produced if the image distance is 6 cm and the object is located at 12 cm in the case of the concave mirror?

    Ans: The magnification of a camera can be determined using the following formula:

    m = -v/u

    Given, v = -6 cm and u = -12 cm

    Sign conventions are used to give the signs.


    m = – (-6cm/ -12cm)

    or, m = -½

    or, m = -0.5

    Consequently, there will be a decrease of 0.5.

    Also read: Optical Fibres and its Types


    What is the magnification of the human eye?

    As humans cannot focus beyond the near point, the maximum magnification of the human eye -in terms of the size of the image that forms on the retina as compared to the size of the object itself -occurs at the near point, when M = 1.7 cm / 25 cm. 068 cm.

    What is magnification power?

    Magnification is defined as the ratio between the image's dimensions and that of the object. In microscopes, lenses, telescopes, and slide projectors, magnification occurs at different levels. The lenses of simple magnifying devices are biconvex - that is, they are thicker at the centre than they are at the edges

    What is the magnification of convex mirrors?

    The image of the object will grow in size as it approaches the mirror, but it will not grow larger than the original object. Convex mirrors always produce a virtual and diminished image. Convex mirrors always have a magnification of less than one.


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