Mirrors, whose reflecting surfaces are curved and can be imagined as part of a sphere, are called spherical mirrors. If the reflecting surface of a spherical mirror is curved outwards, it is called a convex mirror. Whereas a mirror with a reflecting surface, which is bent inwards, is called a concave mirror. Concave mirrors reflect and focus incoming light rays (parallel) at a point, called the focus point. Depending on the distance of an object from the reflecting surface, different types of images are formed. Both kinds of mirrors are used in science and technology. These are used in daily life also. Concave mirrors are used as headlights, torches, head mirrors, solar furnaces, microscopes, telescopes, etc.
A concave mirror is a spherical mirror, which has a reflecting surface, dented inwards. Concave mirrors reflect and focus incoming light rays (parallel) at a point, called the focus point. Depending on the distance of an object from the reflecting surface, different types of images are formed. Concave mirrors are also called converging mirrors since light rays converge after reflection at concave mirrors.
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The uses of concave mirrors are listed below,
Reflecting Telescopes: Concave mirrors are widely used in different reflecting telescopes in observational astronomy. The concave mirror in a reflecting mirror collects the light from distant celestial objects. Since the light sources are very far away, the incoming light rays are effectively parallel. The concave mirror focuses the light rays on a flat mirror, kept at its focal distance. Due to the convergence, the intensity of the light (incident on the flat mirror) increases. Then the reflection of the flat mirror is seen through the eyepiece.
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Microscopes: A concave mirror is used in the base of a microscope as a condenser. The light from an external source is shone on the specimen, after being passed through the mirror. The concave mirror concentrates the light on the specimen only to ensure that the surroundings are relatively dark. The orientation of the mirror can be changed by rotating it. The specimen is seen through an eyepiece.
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Headlights and Torches: The bulb of a headlight or a torch is placed at the focus of a concave mirror. The light rays, coming from the bulb, emerge out as parallel rays after getting reflected at the concave mirror. The reflected rays can cover large distances with high intensity.
Optical Instruments in Medicine: Concave mirrors are used in instruments like ophthalmoscope (used to test the condition of eyes), otoscope (used to observe into ears), and many more. Concave mirrors are also used in simple diagnostic devices called head mirrors, which are used by ENT specialists. The setup is used for proper illumination without shadows in the examining areas.
Dental Mirrors: Dentists used concave mirrors to have a better view of the interior of the mouth.
Optical Cavity: Concave mirrors are used in optical cavities, which play an important role in laser physics. The light rays reflect multiple times inside a cavity and form standing waves.
Solar Furnace: Sunlight is focused on using very large concave mirrors in solar furnaces. The concave mirror gathers a huge amount of sunlight and concentrates it at the focal point. This concentrated energy is used for heating, cooking, generating electricity, or melting metals.
Optical Landing System: The mirror landing aid uses concave mirrors.
Concave mirrors are used in headlights and torches. The shaving mirrors are also concave in nature since these mirrors can produce enlarged clear images. Doctors use concave mirrors as head mirrors to have a clearer view of eyes, noses, and ears. The dental mirrors used by dentists are also concave.
Satellite dishes and visual bomb detectors use concave mirrors.
Concave mirrors are used as reflectors in searchlights. These mirrors help to shine intense collimated beams such that large distances can be observed clearly.
Concave mirrors are used to collimate beams. In experimental physics, the mirror used in a moving coil galvanometer is concave.
Although concave mirrors can focus light from distant sources, the edges of the mirror concentrate the beams at a point that is slightly away from the original focal point. This is called spherical aberration. Reflecting telescopes do face this problem. Due to this aberration, the image of an object becomes slightly distorted.
Depending on the distance of the object, a concave mirror can form a wide variety of images. Some can be enlarged while others can be shrunk in size. This makes any device, using concave mirrors, very sensitive.
1) Write Various Uses of Concave Mirrors in Everyday Life.
Concave mirrors are used as searchlights, shaving mirrors, satellite dishes, and many more. These mirrors have the property to collimate and concentrate light rays. Concave mirrors in torches and headlights are used as reflectors. The source of light is placed at the focus of a concave mirror such that the light rays emerge out as parallel beams, after getting reflected in the mirror.
2) Write Down Two Uses of Concave Mirrors in Science.
Concave mirrors are used in microscopes as condensers. The mirrors are used to shine intense and collimated light at the specimen, to be examined. Reflecting telescopes have concave mirrors to collect light from distant sources. The incoming light rays are focused at a flat mirror, by the concave mirror. The reflection at the flat mirror is finally observed by an eyepiece.
3) Which Mirror is Used in a Solar Furnace? State the Reason.
Large concave mirrors are used in solar furnaces to produce high temperatures and huge amounts of energy at a point (the focus of the mirror). The mirror of a solar furnace gathers sunlight and concentrates the beams at its focus. The concentrated solar energy can be converted into heat and electricity.