# Reflection of Light

## Introduction

In the time when rays come from a source and bounced back, the process is named reflection. The concept of reflection of light was first introduced by Euclid, an ancient Greek Mathematician. At certain times, rays of light often approach a smooth and clear surface and reflect at the same angle.

## What is the Reflection of light?

The reflection mode of light depends on the nature of the surface. After hitting the surface, the rays bounce back in the exact same direction if the surface is polished and smooth (Kittiravechote & Thinarat, 2021). In the case of a rough surface, the rays reflect in a scattered way. The direction of the reflected rays cannot be determined in that situation.

Figure 1: Reflection of Light

The incoming ray or light wave to the surface is known as the incident ray. On the surface, a perpendicular can be imagined that is a normal angle. The angle of incidence is measured by calculating the angle of an incident ray with the base and normal angle (Dambi, 2022).

The ray that is bounced back from the surface is called a reflected ray. The angle of reflection can be measured by calculating the bounce back angle with normal and base direction.

## Types of reflection

There are mainly two significant types of reflection with which the reflection of light can be defined and analyzed.

### Specular reflection

In the time, when a light wave falls on a smooth and polished surface and is reflected at a definite angle, the type of reflection is known as specular reflection. Specular reflection is also known as regular reflection (Emken, 2022).

Specular reflection angle is often found as the exact opposite angle of the incident waves. A clear and most basic example of a specular reflection medium is a mirror. In specular reflection mode, the blurring and haziness of the reflecting image are almost eliminated.

Figure 2: Specular reflection

### Diffusion Reflection

Not all surfaces are smooth and wave-free and in this situation, the incident rays reflect in a scattered way. Most of the surfaces, rather than mirrors possess a rough finish that can include dirt and scratches. As a result, the quality of the reflection and the brightness level deteriorates (Yan et al. 2018).

The angle of diffusion reflection is haphazard and the direction of reflection is different from each other. This type of reflection helps an individual to see any non-shiny object.

Figure 3: Diffusion Reflection

### Multiple reflections

The time when two mirrors are placed in front of an object instead of a single mirror, multiple reflections can happen. A mirror as a reflective surface is very preservative in the intensity of light (de Galarreta et al. 2018).

Two mirrors can produce multiple reflections till the time when the source of light is very low and almost non-seeable. A single image can be seen multiple times, the result of creating a single image within other single images.

Figure 4: Multiple reflections of light

## Laws of reflection

The reflection type of an incident ray is determined by the laws of reflection. In the case of clear water, acting as a reflection surface, the laws of reflection states the following:

a) The angle on the incident ray is equal to the angle of the reflected ray (Xin et al. 2019).

b) Both the incident and reflected ways and the normal lie within the same plane

## Reflection of light on a concave and convex mirror

A concave mirror is used mainly in astronomical telescopes to watch objects that cannot be seen by naked eyes. In this type of mirror, an ample amount of light is collected from a faint source into a very smaller viewing part (Chopineau et al. 2019). Very light rays from a very distant source come straight into the mirror and are reflected in the inward direction to a focal point. In a convex mirror incident rays strike the mirror and reflect back outwards. In this type of reflection, the imaginary lines are centered on a focal point at the very behind of the convex mirror.

Figure 5: Concave and Convex mirror

## Image formation in the concave and convex mirror

Concave mirrorObject's positionImage's positionImage's sizeImage's nature
InfinityFocus pointVery diminishedInverted and real
At point CAt that exact point, CSame as the objectInverted and real
A focus pointInfinityVery EnlargedInverted and real
Between F and PBehind a mirrorEnlargedErect and virtual
Convex mirrorInfinityBehind the mirror and focus on FSized as a pointErect and virtual
Between Mirror's pole P and infinityBehind a mirror and in between F and PDiminishedErect and virtual

Table 1: Image formation types

## Conclusion

The reflection of light takes place based on a law in which, the angle of rays at the time of hitting and the surface nature play an important role. Different types of reflection are there among which specular, multiple, and diffused reflection are the most important ones.

## FAQs

Q1. What is meant by interference?

An important phenomenon, states that two different waves are superposed to form a resultant wave. These waves can be of higher, lower as well as of the same amplitude in nature.

Q2. In which type of reflection, a clear reflection can be produced?

In a regular as well as specular reflection mode, clear reflection can be seen. The nature of the surface plays the most significant role in producing such sharp reflection.

Q3. What is a significant reason behind the changes in direction?

Changes in speed can cause changes in direction of a reflection. The surface nature is also relevant in affecting the direction.

Q4. What is the key difference between refraction and reflection?

Refraction differs from the reflection in many aspects. Reflection is regarded as the reflection of light whereas refraction is the process in which the light shifted its direction during the time of going through a particular medium.

Q5. Which process is known as dispersion of light?

The process in which white light splits into several constituent colors is regarded as dispersion. Dispersion occurs when light passes through a glass prism.

## References

### Journals

Chopineau, L., Leblanc, A., Blaclard, G., Denoeud, A., Thévenet, M., Vay, J. L., ... & Quéré, F. (2019). Identification of coupling mechanisms between ultraintense laser light and dense plasmas. Physical Review X, 9(1), 011050.Retrieved on 10th June 2022 from: https://link.aps.org

Dambi, F. (2022). Emission, Propagation, and Reflection of Light as Mechanical Phenomena. Retrieved on 10th June 2022 from: https://www.preprints.org

de Galarreta, C. R., Alexeev, A. M., Au, Y. Y., Lopez‐Garcia, M., Klemm, M., Cryan, M., ... & Wright, C. D. (2018). Nonvolatile reconfigurable phase‐change metadevices for beam steering in the near infrared. Advanced Functional Materials, 28(10), 1704993. Retrieved on 10th June 2022 from: https://onlinelibrary.wiley.com

Emken, T. (2022). Solar reflection of light dark matter with heavy mediators. Physical Review D, 105(6), 063020. Retrieved on 10th June 2022 from: https://link.aps.org

Kittiravechote, A., & Thinarat, N. (2021, December). Activities on reflection of light based on low-cost materials at eighth grade. In Journal of Physics: Conference Series (Vol. 2145, No. 1, p. 012069). IOP Publishing. Retrieved on 10th June 2022 from: https://iopscience.iop.org

Xin, S., Nousias, S., Kutulakos, K. N., Sankaranarayanan, A. C., Narasimhan, S. G., & Gkioulekas, I. (2019). A theory of Fermat paths for non-line-of-sight shape reconstruction. In Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (pp. 6800-6809). Retrieved on 10th June 2022 from: http://openaccess.thecvf.com

Yan, L. Q., Hašan, M., Walter, B., Marschner, S., & Ramamoorthi, R. (2018). Rendering specular microgeometry with wave optics. ACM Transactions on Graphics (TOG), 37(4), 1-10. Retrieved on 10th June 2022 from: https://dl.acm.org

## Websites

Differencebetween (2022). What is the Difference Between Regular and Diffuse Reflection? Retrieved from: https://www.differencebetween.com [Retrieved on: 10th June 2022]

Geeksforgeeks (2022). Multiple Reflections of Light. Retrieved from: https://www.geeksforgeeks.org [Retrieved on: 10th June 2022]

Peda.net (2022). REFLECTION AT CURVED SURFACES. Retrieved from: https://peda.net [Retrieved on: 10th June 2022]

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Updated on: 13-Oct-2022

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