Reflection, Transmission, and Absorption
In this experiment, you will investigate the relationship between the percent reflectivity of various colors and the temperature change due to energy absorption. Absorption is the transformation of radiant power to another type of energy, The reflectance r is defined by the ratio of reflected radiant power to incident. Absorbed – light energy hitting the surface is converted to heat energy a. Dark or black objects Click on this link to see the video we saw in class on reflection.
If light makes contact with a body, it doesn't mean it is being reflected in any case. It can pass through the body transmission or can be refracted refraction. In case of refraction, the light passes through the body but changes its propagation direction. The most important processes are reflection and absorption.
What is meant by absorption?
Reflection and refraction
Surfaces do not only reflect light; they also absorb it. The light energy is absorbed by the molecules of a body and is then transformed into kinetic energy. The rise in movement of the molecules produces heat which is radiated to the surroundings. The animation below shows the process of absorption in a simplified manner.
The darker a surface, the more sunlight is being absorbed and, thus, more kinetic energy is received by the molecules. The area warms up!
BBC Bitesize - GCSE Physics (Single Science) - Reflection and refraction - Edexcel - Revision 3
Albedo The principles of absorption can be transferred to daily life: A black t-shirt absorbs more sunlight than a white one. This is the reason why we are sweating more wearing a black shirt in summer.
The albedo of a body is crucial for the percentage of absorbed sunlight. It measures the degree of reflection of materials in different spectral ranges. Visible Light Reflection and Transmission Reflection and transmission of light waves occur because the frequencies of the light waves do not match the natural frequencies of vibration of the objects.
When light waves of these frequencies strike an object, the electrons in the atoms of the object begin vibrating. But instead of vibrating in resonance at a large amplitude, the electrons vibrate for brief periods of time with small amplitudes of vibration; then the energy is reemitted as a light wave. If the object is transparent, then the vibrations of the electrons are passed on to neighboring atoms through the bulk of the material and reemitted on the opposite side of the object.
Such frequencies of light waves are said to be transmitted. If the object is opaque, then the vibrations of the electrons are not passed from atom to atom through the bulk of the material. Rather the electrons of atoms on the material's surface vibrate for short periods of time and then reemit the energy as a reflected light wave.light absorb reflect refract
Such frequencies of light are said to be reflected. Where Does Color Come From? The color of the objects that we see is largely due to the way those objects interact with light and ultimately reflect or transmit it to our eyes. The color of an object is not actually within the object itself. Rather, the color is in the light that shines upon it and is ultimately reflected or transmitted to our eyes.
We know that the visible light spectrum consists of a range of frequencies, each of which corresponds to a specific color. When visible light strikes an object and a specific frequency becomes absorbed, that frequency of light will never make it to our eyes.
Any visible light that strikes the object and becomes reflected or transmitted to our eyes will contribute to the color appearance of that object.
Light Absorption, Reflection, and Transmission
So the color is not in the object itself, but in the light that strikes the object and ultimately reaches our eye. The only role that the object plays is that it might contain atoms capable of selectively absorbing one or more frequencies of the visible light that shine upon it. So if an object absorbs all of the frequencies of visible light except for the frequency associated with green light, then the object will appear green in the presence of ROYGBIV.
And if an object absorbs all of the frequencies of visible light except for the frequency associated with blue light, then the object will appear blue in the presence of ROYGBIV. Consider the two diagrams below. The papers are impregnated with a chemical capable of absorbing one or more of the colors of white light.
Reflection, Absorption & Transmission - Maggie's Science Connection
Such chemicals that are capable of selectively absorbing one or more frequency of white light are known as pigments. In Example A, the pigment in the sheet of paper is capable of absorbing red, orange, yellow, blue, indigo and violet.
In Example B, the pigment in the sheet of paper is capable of absorbing orange, yellow, green, blue, indigo and violet.