Concave Mirror & Convex Mirror

Everything visible around us is visible because of light. When light rays from the source object have reflected the observer, this happens. The light source should be a polished or shiny surface that acts as a mirror for a good reflection. This is due to a phenomenon known as light reflection, which does not change the velocity of light but reverses the direction of incident light. A spherical, smooth and shiny surface is required for good light reflection.

As a result, the spherical mirror is made by cutting out a hollow spherical glass ball. Depending on the application, the reflecting surface of a spherical mirror can be inside or outside.

Spherical Mirror Types

There are two kinds of spherical mirrors:

• Mirrors with Concave Surfaces

If a hollow sphere is cut into some parts and the outer surface of the cut part is painted, it becomes a mirror, with the inner surface reflecting. It results in a concave mirror.

• Spherical-shaped mirrors

A shining spoon’s curved surface can be compared to a curved mirror. The most common type of curved mirror is the spherical mirror. The reflecting surface of such mirrors is considered a part of any sphere’s surface. Spherical mirrors are mirrors with spherical reflecting surfaces.

A concave mirror, also known as a converging mirror, is a mirror that is bent in the middle towards the inside. Furthermore, looking into this mirror will make us feel like we are looking into a cave. Therefore, we usually use the mirror equation when dealing with a concave mirror.

The mirror’s equation determines the object’s position and its exact size. However, the angle of incidence in a concave mirror is not the same as the angle of reflection. Furthermore, in this case, the angle of reflection is determined by the area on which the light falls.

Concave Mirror Properties:

Light after reflection converges at a point when it strikes and reflects from the concave mirror reflecting surface. As a result, it is also known as a converging mirror.

A magnified and virtual image is observed when the converging mirror is placed very close to the object.

However, as the distance between the object and the mirror increases, the size of the image decreases and a true image is formed.

The image formed by the concave mirror can be small or large, real or virtual.

Concave Mirror Applications:

• Converging mirrors are most commonly used in shaving mirrors due to their reflective and curved surfaces. When shaving, the concave mirror forms an enlarged and erect image of the face as it is held closer to the face.

• Concave mirrors used in ophthalmoscopes: These mirrors are used for treatment in optical instruments such as ophthalmoscopes.

• Concave mirror applications in astronomical telescopes: These mirrors are also widely used to manufacture astronomical telescopes. The objective of an astronomical telescope is a converging mirror with a diameter of about 5 metres or more.

• Concave mirrors used in vehicle headlights: Converging mirrors are widely used as reflectors in automobile headlights and motor vehicles, torchlights, railway engines and so on. 

• Because the point light source is kept at the mirror’s focus, the light rays travel over a large distance as parallel light beams of high intensity after reflection.

• Large converging mirrors are used in solar furnaces to focus sunlight to produce heat in the solar furnace. They are frequently used in solar ovens to collect a large amount of solar energy in the concave mirror’s focus for heating, cooking, melting metals and so on.

The shorter the focal length, the more powerful the mirror; thus, P = 1 f applies to mirrors. A mirror with a more strongly curved surface has a shorter focal length and more power. The focal length is half the radius of curvature or f = R 2, by the law of reflection and some simple trigonometry.

In which R is the spherical mirror’s radius of curvature. The shorter the focal length and thus the more powerful the mirror, the smaller the radius of curvature.

A convex mirror with a focal point gives Parallel rays of light reflected from the mirror appear to originate from the point F behind the mirror at the focal distance f. Because it is a diverging mirror, a convex mirror’s focal length and power are negative.

Mirrors and lenses both benefit from ray tracing. The ray-tracing rules for mirrors are based on the following illustrations:

• A spherical convex mirror. After reflection, a beam of parallel rays on the mirror appears to come from F on ray 2 behind the mirror. 
• Parallel rays of light reflected from a convex spherical mirror (small in size compared to its radius of curvature) appear to come from a well-defined focal point behind the mirror at the focal distance f. Convex mirrors have a negative focal length because they diverge light rays.

Conclusion:- 

We will use ray tracing to demonstrate how mirrors create images and we’ll be able to use it quantitatively to obtain numerical data. However, because each mirror is small in comparison to its radius of curvature, the thin lens equations can be used for mirrors just as we did for lenses.