Resolving power of today's digital sensors (especially those in compact cameras and cellphones) greatly exceeds that of any film. The magnification (m) of lens can also be calculated in terms of image distance (v) and object distance (u), if we do not know the size (height) of object and image. Also, find the magnification produced by the lens. What do you meant by magnification of a lens. Lens formula is applicable for convex as well as concave lenses. On the other hand, the magnification m is negative when the image formed is real and inverted. For example, if the eyepiece magnification is 10x and the objective lens in use has a magnification of 4x, the total magnification is 10 × 4 = 40. It is an equation that relates the focal length, image distance, and object distance for a spherical mirror. It is given as. Where f is the focal length of the lens used. Required fields are marked *. Test Your Understanding and Answer These Questions: The magnification of a lens may be defined as the ratio of the size (height) of the image to the size (height) of the object. SI unit of power is Dioptre (D). It is represented by the symbol m. The size of an image formed by a lens varies with the position of the object. Magnification with a Bi-Convex Lens - Java Tutorial . For instance, a lens that makes a small object appear very big has a high magnification, while a lens that makes an object appear small has a low magnification. Thus, Rules for Obtaining Images by Spherical Lenses. The total magnification of a low power objective lens combined with a 10x eyepiece lens is 100x magnification, giving you a closer view of the slide than a scanning objective lens without getting too close for general viewing purposes. For example, if the eyepiece magnification is 10x and the objective lens in use has a magnification of 4x, the total magnification is 10 × 4 = 40. Thus, Where, v = image distance u = object distance. Spherical lenses are the lenses formed by binding two spherical transparent surfaces together. The total magnification of 40 means that the object appears forty times larger than the actual object. Sample objective magnifications. Convex lens: The lenses formed by binding two spherical surfaces bulging outward are known as convex lenses. Thus, Where, h2 = size of image h1 = size of object. Please note that the magnification formula is applicable both in convex lenses and concave lenses. It is equal to the ratio of image distance to that of object distance. The power of the concave lens is negative, while the power of the convex lens can be positive. The image distance can be calculated with the knowledge of object distance and focal length with the help of lens formula. Convex lenses are also known as converging lenses since the rays converge after falling on the convex lens while the concave lenses are known as diverging lenses as the rays diverge after falling on the concave lens. The power of a lens is the measure of the degree of convergence or divergence of the light rays falling on it. Magnifying Glass. Thus, we define the power of the lens as the reciprocal of the focal length of the lens used. Figure 1. This equation is used to find image distance for either real or virtual images. If this equation shows a negative focal length, then the lens is a diverging lens rather than the converging lens. Optical magnification is the ratio between the apparent size of an object (or its size in an image) and its true size, and thus it is a dimensionless number. Simple Lenses: It refers to a simple lens that we use to magnify an object. The degree of convergence or divergence depends upon the focal length of the lens. Your email address will not be published. These lenses have negligible thickness.