Describe an activity to show that the incident ray, the reflected ray and the normal at the point of incidence lie in the same plane.
Solution and Explanation
Fix a white sheet of stiff paper on a drawing board or a table. Take a comb and close all its openings except one in the middle. Hold the comb perpendicular to the sheet of paper. Throw light from a torch through the opening of the comb from one side. With slight adjustment of the torch and the comb we will see a ray of light along the paper on the other side of the comb. Keep the comb and the torch steady. Place a strip of plane mirror in the path of the light ray. Let the sheet project a little beyond the edge of the Table. Cut the projecting portion of the sheet in the middle. Look at the reflected ray. Make sure that the reflected ray extends to the projected portion of the paper. Bend that part of the projected portion on which the reflected ray falls. Bring the paper back to the original position.
When the whole sheet of paper is spread on the table, it represents one plane. The incident ray, the normal at the point of incidence and the reflected ray are all in this plane. When we bend the paper you create a plane different from the plane in which the incident ray and the normal lie. Then we do not see the reflected ray. It indicates that the incident ray, the normal at the point of incidence and the reflected ray all lie in the same plane.
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Concepts Used:
Reflection of Light
Reflection of light is the process by which light waves bounce off a surface when they encounter it. It is a fundamental phenomenon that plays a crucial role in our everyday experiences with light and vision.
When light waves strike a surface, three possible outcomes can occur: absorption, transmission, or reflection. In the case of reflection, the light waves are neither absorbed nor transmitted but instead are redirected back into the original medium.
The angle of incidence, which is the angle between the incident light ray and the perpendicular to the surface, is equal to the angle of reflection, which is the angle between the reflected light ray and the perpendicular to the surface. This relationship is described by the law of reflection.
The law of reflection states that the incident ray, the reflected ray, and the normal (perpendicular) to the surface at the point of incidence lie on the same plane. Additionally, the angle of incidence is equal to the angle of reflection.
The reflective properties of a surface depend on its smoothness and nature. A smooth, polished surface, such as a mirror, exhibits regular or specular reflection, where light waves are reflected in a well-defined direction, resulting in a clear image. On the other hand, a rough or uneven surface exhibits diffuse reflection, where light waves are scattered in various directions, leading to a blurred or scattered reflection.
The reflection of light is utilized in numerous practical applications. Mirrors are used for reflection in optics, photography, and everyday objects like mirrors in households and vehicles. Reflective surfaces are employed in optical systems, such as telescopes, microscopes, and laser devices. The understanding of light reflection is also vital in architectural design, where the reflection of natural light is harnessed to enhance lighting and energy efficiency in buildings.
Overall, the reflection of light is a fundamental phenomenon that enables us to perceive the world around us, and its principles find application in various scientific, technological, and practical domains.