Final answer:
The law of reflection states that the angle of incidence equals the angle of reflection. When powder is applied to a person's nose, it creates a rough surface, causing diffuse reflection which reduces the shine or glare.
Step-by-step explanation:
The law of reflection states that when light hits a smooth surface, the angle of incidence (the angle between the incident light ray and the normal to the surface) is equal to the angle of reflection (the angle between the reflected light ray and the normal to the surface).
When powder is applied to a person's nose, the powder particles create a rough surface. When light falls on this rough surface, it undergoes diffuse reflection. In diffuse reflection, the incident light is reflected in many different directions due to the irregularities on the surface. As a result of diffuse reflection, the shine or glare on the person's nose is reduced.
The name of the optical effect when the shine is reduced due to powder is diffuse reflection.