The law of reflection states that the angle of incidence is equal to the angle of reflection.

When a light ray encounters a surface, it can be absorbed, transmitted, or reflected. The law of reflection specifically pertains to the behavior of reflected light. It asserts that the angle of incidence, denoted as the angle between the incident ray and the normal (a line perpendicular to the surface), is equal to the angle of reflection, which is the angle between the reflected ray and the normal. This principle applies universally to all types of surfaces, including flat, curved, and rough surfaces.

Understanding the law of reflection is essential for comprehending how mirrors function. When light strikes a mirror, it is reflected back at the same angle as the angle of incidence, allowing us to see a clear image of ourselves in the mirror. This principle also plays a crucial role in the design of various optical instruments, such as telescopes and microscopes.

Mathematically, the law of reflection can be expressed with the equation:

where $\theta_i$ represents the angle of incidence and $\theta_r$ represents the angle of reflection. This equation can be utilized to determine the angle of reflection if the angle of incidence is known, and vice versa.

In summary, the law of reflection is a fundamental principle in optics that describes how light reflects off surfaces. It is vital for understanding the behavior of light and is instrumental in the design of optical devices.