According to the law of reflection, when a ray of light reflects off a surface, the angle of incidence is equal to the angle of reflection.
The reflected ray always meets the surface normal at the point of contact between the incident ray and the plane defined by the incident ray and the surface normal.
A plane mirror or curved mirror produces images that are explainable by the law of reflection. The laws of reflection hold good for light reflected from any smooth surface.
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An incident ray, a reflected ray, and the surface's normal lie in the same plane when they fall on a smooth surface; also the angles of reflection and incidence are equal. The beam of light striking the reflecting surface is called the incident ray.
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Reflection occurs when light traveling through one material bounces off a different material. The reflected light still travels in a straight line, only in different directions. It depends on the interface if the light is specular (mirror-like) or diffuse (keeping the energy but losing the image).
Reflection of specular light occurs through a mirror, which is usually made up of a glass sheet with a metallic coating that captures the light. As waves propagate beyond their skin depths, metals exhibit enhanced reflection.
Using the diagram, a vertical mirror O is struck by a light ray PO, producing reflected light OQ. The reflection of light can happen when light travels from a medium whose refractive index is one of the means of propagation into another medium whose refractive index is different, for reflection examples. It is generally true that in the most general case, some of the light is reflected and the remainder is refracted.
By putting Fresnel's equations into practice for a light ray striking a boundary, it is possible to determine what percentage of the light is reflected and for what percentage it is refracted. Analogous to the way impedance mismatches cause signals to be reflected in electric circuits.
An angle of incidence greater than the critical angle will result in a total internal reflection of light from a denser medium.
Reflection light of high refractive index materials shifts it 180° relative to the medium traveling. The reflected light is phase-aligned with the incident light when it reflects off a material with a lower refractive index. Thick-film optics uses this principle to explain many of its basic principles.
An image is formed by specific reflections. If we rotate the image, we see, the image appears reversed, as if it had been reflected from a flat surface. A curved mirror may have optical power; curved reflections form images that may be magnified or demagnified. Typically, spherical or parabolic mirrors have spherical or parabolic surfaces.
S. No. | Regular Reflection | Irregular Reflection |
1 | When all reflected rays from a smooth surface are parallel to incident rays. | This is when incident parallel rays do not remain parallel to each other, the reflected rays do. |
2 | Smooth surfaces, such as mirrors, silver spoons, etc. provide this texture. | Rusty surfaces such as wood, doors, tables, books, etc. provide this texture. |
3 | The image is formed and seen. | It helps to see objects. |
If an object lies beyond the focus of the mirror, then concave mirrors produce actual, inverted images, while a virtual, erect, enlarged image appears when the object lies closer to the focus.
The result is always a mirror image that looks erect and diminished.
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If light passes from a denser medium to a lighter medium at an angle greater than the critical angle necessary for refraction, it will reflect into a denser medium. Total Internal Reflection refers to this phenomenon. The ordinary laws of reflection for light also govern light that undergoes a total internal reflection:
A curved path is created by the phenomenon of total internal reflection. Fibre-air interfaces are large enough to cause light reflected from narrow fibres of glass or plastic to repeatedly exceed the critical angle. Light can be transmitted over long distances without losing intensity when it passes through optical fibres.
An optical fibre network uses pulses of light to transmit information using total internal reflection. An optical fibre bundle is used by instruments such as endoscopes to image internal organs through total internal reflection.
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Periscopes use reflection to observe advancing enemies on the battlefield from a safe distance.
We see objects because of reflections.
As mentioned above, mirrors with concave and convex surfaces can reflect a variety of different images.
Medical diagnostics rely on reflection, as does optical communication.
The law of reflection governs both light and sound, as both are waves.
Our ability to measure distances accurately to objects is based on the law of reflection for sound and light.
The echoes of sound are the result of reflections.
NCERT Physics Notes:
Q1. An incident ray of light strikes a plane mirror at an angle of 30° with the mirror surface. Approximately what angle will the reflection be?
Ans: The angle of incidence is determined by comparing the incident ray with the normal, so it is not 60° in this case
Following the Law of reflection,
θ i = θ r
Hence,
The angle of reflection = 600
Q2: Determine the angle * which would be made by the system of the two mirrors shown in the figure below so that A and B are parallel to one another.
Ans: Here is a diagram in which we fill in the angles of incidence and reflection and also label the rays as they are incident and reflected.
Angles I + r and i' + r’, which represent the incident wave at A and the reflected wave at B, have to be supplementary. (Geometry: cross-section cut between parallel lines).
Therefore,
i + r + i’+ r’ = 180 °
As a result of the law of reflection, i = r and r' = i'
Substitute to obtain
i + i + i’ + i’ = 180 °
i + i’ = 90
In triangle AOB, we have
α + (90 – r) + (90 – i’) = 180 °
α = r + i’ = i + i’ = 90 °
If α = 90 °, the downward ray passes through A and the upward ray passes through B.
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Periscopes use reflection to observe advancing enemies on the battlefield from a safe distance.
We see objects because of reflections.
The light is reflected back into the denser medium when it passes from a denser medium to a lighter medium at an angle greater than the critical angle for refraction. Total Internal Reflection refers to this phenomenon.
Objects beyond the focus of a concave mirror give real, inverted images. Objects within the focal range of a concave mirror give a virtual, erect, enlarged image.
It is known as the reflection of light when light rays hit the surface and bounce back.
A smooth surface is defined as having an angle equal to that of the reflected ray on reflection. The angle is equal to the angle between the incident and reflected rays that is parallel to the line perpendicular to the surface at the point of contact.
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