To understand the concept of a mirror, it is necessary to know what is the phenomenon behind the mirror and what makes it a reflective material. A mirror is described as a reflective surface, and it follows the law of reflection. According to the law of reflection when a ray of light is made to fall on the reflective surface, the reflected ray has its angle of reflection, incident rays, and the reflected rays are natural to the surface at a point of incidence.
Realities To Mirror
- Incident ray: It is defined as a luminous ray that hits the surface.
- Reflected ray: It is defined as the ray of light that, after hitting the surface, reflected backward.
- Normal ray: It is known as the 90° ray to the surface or the ray perpendicular to the reflecting surface.
- Refracted ray: It is known as the incident ray that passes through a second medium resulting in directional change.
- The angle of incidence: The angle between the incident is defined as radiating the normal at which the incidence occurs.
- Reflection angle: This is known as the angle between the reflected ray and normal at which the reflection takes place.
- Refraction angle: This is defined as the angle between the refracted ray and the normal at which refraction occurs.
These are the most commonly used forms of mirrors:
The images that are created from a plane mirror are the images that are reflected in their regular proportions but rotated from left to right. Those are the mirrors that are most commonly used.
These are the spherical mirrors that are curved outward, and the image obtained for a real object is virtual, diminished, and erect.
These are the inward curved spherical mirror, and the image obtained from such mirrors depends on the object’s location.
Nature of image with respect to the position of the object
1. The positioning of object – Set at infinity
Retrieved image – Highly reduced, real and inverted
2. The positioning of object – Positioned beyond the center of curvature
Retrieved image – Reduced, real and inverted
3. The positioning of the object – Positioned in the center of curvature
Retrieved image – Similar size as the object, actual and inverted
4. The positioning of object – Positioned between the center of curvature and the focus
Retrieved image – Expanded, actual and inverted
5. The positioning of the object – Placed at the focus of the principle
Retrieved image – Highly enlarged, real and inverted
6. The positioning of object – Placed between the principle of focus and the pole
Retrieved image – Image is obtained behind the mirror, highly enlarged, virtual and erect
Working of a Mirror
We know the light is energy, and it can either reflect or absorb. Light gets reflected when it falls on the reflecting surface. The light energy is reflected in the mirrors.
It is the reason why the only reflection comes from mirrors and not the other flat white surfaces because, at a microscopic point, the mirror is smooth. The light bounces back into all directions when the light energy hits the rough surface, and this is known as diffuse reflection. But for a smooth surface, the light bounces back in one direction and is known as specular reflection.
Uses of concave mirrors
A concave mirror is called as converging mirror, has its reflective surface bulging inward, i.e., away from the incident ray. Numerous applications of the concave mirrors are found in our daily life. It is used to direct the aircraft in the aircraft landing. It is used as a torch to reflect the light rays. It is used during shaving to achieve an upright and expanded image of the face, etc.
Some uses of the concave mirror are listed in the points below.
- Rashing mirrors
- Mirrors to the head
- Astronomical telescopes
- Solar furnaces
Used in shaving mirrors
Due to its reflective and curved surface, concave mirrors are most commonly used in the shaving. When the mirror is held nearer to the face, the concave mirror forms an enlarged and erect image of the face during the shaving.
Used as a head mirror
The specialist E.N.T. also uses concave mirrors. They put on the front of their patient’s concave mirror. As the light rays from the light source are reflected from the concave mirror, they are focused on the patient’s head, nose, or mouth, rendering the infected parts more apparent.
The concave mirror uses in the Ophthalmoscope
Concave mirrors are used in optical instruments like Ophthalmoscope. Ophthalmoscope has a concave mirror that has a hole in the middle. The doctor focuses from behind the concave mirror through the tiny hole as a light beam, which is directed through the patient’s eye pupil. That makes the retina visible and makes testing simple for doctors.
Uses of the concave mirror in astronomical telescopes
Concave mirrors are used for the manufacturing of astronomical telescopes too. A concave mirror with a diameter of 5 meters or more is used as a target in an astronomical telescope.
Concave mirrors used in headlights
Concave mirrors are commonly used as reflectors in car and motor vehicle headlights, torch lights, railway engines, etc. The light source is positioned at the mirror ‘s focus so that high-intensity parallel light beams fly over a large distance after reflecting the light rays.
Used in solar furnaces
Large concave mirrors are used to focus the sunlight on the solar furnace to produce heat. They are used in solar ovens to accumulate a large amount of solar energy for heating, cooking, melting metals, etc., in the concave mirror focus.
These were some common everyday uses of the concave mirror. Concave mirrors are used in satellite dishes, optical microscopes, detectors of visual bombings, etc.
Concave mirrors reflect focal light inwards. Hence they are mostly used for focusing on light. A concave mirror displays different types of images, depending on the distance between the mirror and the object. Concave mirrors are called converging mirrors because they absorb the light when it falls on the mirror, and refocuses the incoming parallel rays. A mirror is an optical tool that forms an image by gathering the light.
Whether we see ourselves in mirror we see a replica of our self looking back at us. We wink it winks back. The way we look in mirror is always not exactly what we look in real life. We may appear small, tall, fat or even upside down depending on the type of mirror. Images formed can be of two types-real and virtual.
The images that are formed inside the mirror are virtual images. Virtual images are those which you can only see but cannot touch. They are not present in real life. Real images are those formed on the mirror itself and can be seen in front of the mirror without looking into the mirror. Only a few mirrors can produce real images.
Types of Mirror
With the advent of technology mirrors have changed their surfaces from flat to curve. Flat mirror were previously used for decorative purposes and also as a looking glass. With the invention of curved mirrors more uses have come to existence and it is getting used in different fields. There are two types of curved mirrors mostly-
- Convex mirror and
- Concave mirror
Convex mirror- convex mirrors have surfaces curved outwards. They have bulge in the middle. Their main task is to diverge any sort of rays falling on. These mirrors usually form virtual images that cannot be reproduced on a physical plane or screen.
The topic of emphasis of this text, however, is, Concave mirror- concave mirrors have surfaces curved inwards. They have depression in the middle. Their main task is to converge any sort of rays falling on them. Concave Mirrors are converging mirror which have depression in the middle as compared to the periphery.
These mirrors are converging mirror and can convert the entire race coming towards it to a focal point which lies on the focal arc. Any two parallel rays coming towards a concave mirror will convert at the focus on the focal arc. Since concave Mirrors always focus the light rays which intersect at a Focal point, the images formed by these Mirrors are always real in nature.
This means ladies images can be projected on a physical plane. Because of the converging nature of these Mirrors they find variety of applications in everyday uses.
However there is a small problem with these mirrors. These Mirrors for men image that is usually smaller in nature than the actual image that would have been obtained if there was a plane mirror instead of the spherical mirror.
Uses of Concave Mirror
It is used in vehicles as rear view mirrors. These make the vehicles to appear closer than they really are. Thus allowing the driver to know what is behind him and how far it is and allows him to see a detailed and clear picture because of it magnified image.
Large concave Mirrors are used in reflecting telescopes which collect light rays from far away and convert them at another concave mirror which in turn converges them to a lens that magnifies the image forming a clear image of faraway object.
Most professional telescopes used for astronomical purposes are usually reflecting type using a concave mirror because this type of mirror provides cheap and vibrations free alternative to delicate lenses used in a refracting telescopes. Most satellite telescopes and observatories employing reflecting telescopes employing concave lenses
It is used as shaving mirrors or for applying makeup. Concave mirror has an interesting property in which is an object is close enough to the mirror that is if it falls within the focal length of the mirror then it produces an enlarged, upright and virtual image of the object.
This feature is particularly useful as shaving mirror which help in carefully shaving providing added safety. Since it also helps to catch the details of the face it also is used as mirrors in makeup rooms and makeup kits.
in illumination applications, concave mirrors are used to gather light from a small source and direct it outward in a beam as in torches, headlampsand spotlights. Because concave Mirrors can concentrate like they are used in illumination applications where light needs to be directed in to a particular direction.
Usually car headlamps and Search Light use concave mirrors with the light bulb or source in the focus so that it can reduce parallel like trees that can help us with proper powerful and interference-free illumination providing clear visibility.
It is also used in solar power to collect light from a large area and focus it to a single point. Solar heaters are the future of efficient energy utilization and sustainable subsistence.
These haters use large concave Mirrors that can Converse the highly energetic solar radiation to a single point producing enormous amount of heat that can be utilized in generation of huge amounts of power which can not only be used for domestic purposes like hitting water and room heating but also can be used to produce steam to run conventional turbines to produce electricity.
Concave mirrors are used to form optical cavities which are important in laser construction
Dentists make use of concave mirrors to form high quality magnified image of the inner walls of the mouth as well as the teeth for the purpose of effective examination and proper subsequent diagnosis. The mirror landing aid system of modern aircraft carriers also uses a concave mirror.
The primitive microscope used concave mirrors to channel light into the subject to be observed under the lenses which provided better visibility of the specimen in the slide.
Because concave Mirrors have a very good ability to concentrate energy they have been also showed to concentrate certain kinds of high energy radiation that has been used to manufacture new types of invasive machines that employee concentrated laser technology.
These machines usually find application in the formation of new age weapons systems which operate without the use of conventional projectiles and recoil mechanism. This technology is also useful to manufacture surgical instruments for cutting or destroying tumors and stones within the body result in minimum invasion and maximum output.
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