We are faced daily with several situations in which the use of a mirror is necessary, whether it is used in the car's rearview mirror, when we go to comb our hair, in the elevator, etc.
Sometimes our goal is to magnify the reflected image, for example, in a telescope, or collect sunlight and use it as thermal energy to heat the water in the water tank, or see our face in detail, whether to shave it or retouch the makeup. In the examples cited we make use of concave mirrors.
In very different situations, we could try something that might seem impossible, like putting the image of a huge building, or put inside the rear view mirror of the Beetle 79 the image of the huge truck that is soon back. In the cases of these examples we make use of convex mirrors, which, due to their format, present a larger visual field, thus surpassing flat mirrors. We make the comparison by looking at the figure below.
Comparison between the visual field of a plane mirror and a spherical mirror
Although it is widely used, great care must be taken when using the convex mirror as a rearview mirror, as the image we obtain in it is reduced and appears close to the mirror. This can cause serious inconvenience to a car driver.
For lighting purposes, concave mirrors are used as light reflectors. This is the case of street lighting, industrial lighting and car headlights. Not always, however, the mirror used is the spherical one, but the parabolic one.
In order to obtain a beam of light with parallel rays, the source is placed in the focus of the concave mirror E1 (spherical or parabolic). This focus must coincide with the center of curvature of a second mirror E2, also concave, to increase the luminous efficiency of the reflector.
By Domitiano Marques
Graduated in Physics
Brazil School Team
Source: Brazil School - https://brasilescola.uol.com.br/fisica/os-espelhos-esfericos-no-cotidiano.htm