Have you ever thought about how does your dressing table mirror work? How can you see yourself in the mirror? Certain concepts can answer your questions about the working of plane mirrors. Ray Optics in physics explains the movement of light to create the images you can see in the mirror.
Ray Optics
The field of optics defined as ray optics, commonly called geometric optics, uses the idea of rays to express how light behaves. Without considering light’s wave-like nature, it studies light propagation and how it interacts with different optical devices, including lenses, mirrors, and prisms.
In ray optics, light is a group of rays moving in a single direction. These rays are imaginary lines that indicate the course and direction of light as it travels through space. The fundamental ideas and rules governing how these beams behave in relation to optical elements are the main focus of ray optics.
Law of Ray Optics
Certain laws govern the concepts of ray optics:
Law of Reflection
According to the law of reflection, the angle of incidence (θi) is equal to the angle of reflection (θr), and both of these angles are calculated in relation to the normal, which refers to a line parallel to the surface of the interface that is present at the point of incidence. This law governs the reflection of light rays by plane mirrors and flat surfaces.
Alt text: Law of Reflection
Snell’s Law (Law of Refraction)
The law of refraction, sometimes called Snell’s law, defines how light rays change their path as they move from a certain medium to another medium with a varying refractive index. It shows that the ratio of the refractive indices of the two media is equal to the sine of the angle of incidence (sin θ1) to the sine of the angle of refraction (sin θ2).
Alt text: Refraction of light
Law of Total Internal Reflection
The law of total internal reflection is an optics law that defines the phenomena that occur when light travelling in a medium with a higher refractive index reaches an interface with a medium with a lower refractive index at an incidence angle greater than the critical angle. In these scenarios, the light is reflected the incident medium rather than refracting (bent) at the contact.
Alt text: Total internal reflection
What is a Plane Mirror?
According to the law of reflection, a plane mirror is a smooth, flat surface reflecting light. Plane mirrors are often utilised for everyday settings, such as household mirrors, dressing rooms, and car rear-view mirrors.
The characteristics of an image formed by a plane mirror are as follows:
1. A plane mirror always creates a virtual image that cannot be displayed on a screen. It is created by the perceived intersection of light rays that have been reflected.
2. A plane mirror creates an upright image.
3. The image created through a plane mirror is equal in size to the object.
4. A plane mirror forms an image laterally inverted and is called a mirror image.
5. The image formed by the plane mirror is at the equivalent distance behind the mirror as the distance between the object and the mirror. The distance between the mirror and an object is the same as between the mirror and the image.
Conclusion:
The answer to our question on how the mirror function is the reflection of light, which helps create the images in the mirror. With the help of ray optics, you can easily understand the working of a plane mirror. The plane mirror has a reflecting surface; the other is a non-reflecting dark surface. The rays of light then get reflected on the shiny reflecting surface of the mirror; we can see the image of any object.
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