7-1 Perambatan Cahaya pada Material: Refleksi

Summary

In this physics course, Dr. Rizkiyanto Mangkuto delves into the concept of light propagation in materials, with a focus on reflection phenomena. The lecture explores different types of light reflection, such as diffuse, specular, and glossy reflections, and their impact on photometric quantities. Dr. Mangkuto explains key concepts like reflectance, the ratio of reflected light flux to received light flux, and introduces important parameters such as illuminance and excitation. The session emphasizes the relevance of reflection in photometry, providing students with crucial insights into the behavior of light in built environments.

Takeaways

• 😀 Light propagation in materials is a phenomenon of interaction between light and materials in the built environment.
• 😀 The impact of light propagation on photometric quantities in built environments is significant.
• 😀 There are several types of light propagation in materials, including reflection, which will be discussed in this segment.
• 😀 The reflection phenomenon is highly relevant in photometry and is often used in building physics.
• 😀 Matte or Map surfaces cause diffuse reflection, where reflected light is spread in all directions.
• 😀 Specular reflection occurs when light is reflected at the same angle as the angle of incidence, like a mirror.
• 😀 Diffuse reflection gathers the reflected light around the angle of incidence, with the surface being shiny or glossy.
• 😀 Reflectance (roh) is used to quantify the magnitude of light reflection, representing the ratio of reflected light flux to received light flux.
• 😀 Reflectance is calculated using the ratio of reflected excitation (Mr) to illuminance (Ie).
• 😀 The reflectance equation involves dividing reflected light flux by received light flux, incorporating surface area into the calculation.

Q & A

What is the main topic discussed in this lecture segment?

The main topic discussed is the propagation of light in materials, specifically focusing on the phenomenon of reflection and its relationship to photometric quantities in a built environment.

What is the definition of light propagation in materials?

Light propagation in materials refers to the interaction between light and materials in a built environment and its effect on the photometric quantities produced.

What are the different types of light propagation in materials?

The different types of light propagation in materials include reflection, diffusion, and specular reflection.

What is the phenomenon of reflection, and why is it relevant?

Reflection is the phenomenon where light bounces off a surface. It is relevant because it is commonly used in photometry to understand how light interacts with surfaces and materials.

What is diffuse reflection?

Diffuse reflection occurs when the intensity of reflected light is spread in all directions, and it typically happens on matte surfaces.

What is specular reflection?

Specular reflection occurs when light reflects off a surface at the same angle as the angle of incidence, typically occurring on smooth, mirror-like surfaces.

How does the surface texture affect reflection?

The surface texture affects reflection by determining whether the reflection is diffuse (spread in all directions, like on a matte surface) or specular (focused at the angle of incidence, like on a smooth surface).

What is the reflectance parameter, and how is it calculated?

The reflectance parameter, denoted as 'roh', is the ratio of the total reflected light flux to the total light flux received by a surface. It is calculated by dividing the reflected light flux by the received light flux.

What does the reflectance value represent in the context of light reflection?

The reflectance value represents how much light is reflected by a material compared to how much light it receives. It is a key factor in determining the material's ability to reflect light.

What is the relationship between reflected excitation and illuminance in this context?

The relationship between reflected excitation (Mr) and illuminance (Ie) is represented by the reflectance formula, where reflectance (roh) equals the ratio of reflected excitation to illuminance, normalized by the surface area.