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The light we see is always travelling in straight lines. To easily describe its path theoretically, the concept of a ray of light is used to demonstrate the direction and path travelled by light. Light rays reflect off from an object into our eyes, and we see the object via reflection. On the other hand, if an object is luminous or giving off light, it further emits rays of light in every direction, and that emitted light goes into the eyes, making the object visible. The light ray falling on an object at its surface always bounces back in the same rays. This phenomenon is known as reflection, and the rays are called reflected rays.
There are two laws of reflection:
- The angle of incidence is equal to the angle of reflection.
- The incident ray, reflected ray, and the normal at the point of incidence, are found in the same plane.
Reflection On a Plane Mirror
Whenever a light (waveform) travels in one medium that receives a boundary of another medium with a different refractive index, a part of that lightwave always bounces back into the first given medium, known as the reflection of a light ray. There can always be some part of the same light rays that may/may not pass through the second medium, and this phenomenon is called refraction.
The same happens with mirrors. A plane mirror is a flat, smooth surface that reflects most of the light received by it. Light rays that fall on the flat mirror always get reflected back. Here too, the laws of reflection work and are taken into account. Think for a moment that the incident ray makes an angle with the normal line to the surface. That angle is called the angle of incidence, represented by θi. That ray will surely reflect back; let that reflected ray make an angle with the normal line to the mirror’s surface; this is called the angle of reflection, θr. The aforementioned law of reflection states that the angle of reflection (θr) will always be equal to the angle of incidence (θi).
Characteristics of Images Formed by a Plane Mirror
The following are characteristics of images formed by a smooth plane mirror:
- The image obtained by a smooth plane mirror is always erect, straight, and not real (virtual).
- The image obtained after reflection is the same size as that of the object, and both are always equal.
- After you see the reflection, the distance between the image from the mirror is equal to the distance between the object and the placement of the mirror.
- Images obtained from the reflection of a plane mirror are laterally inverted (the left is seen towards the right, and the right is seen towards the left).
Conclusion
Light rays reflect off from an object into our eyes, and the way we see the object is via reflection. Whenever a light (waveform) travels in one medium that receives a boundary of another medium with a different refractive index, a part of that lightwave always bounces back into the first given medium, known as the reflection of a light ray. Images obtained from the reflection of a plane mirror are laterally inverted.
