Question

On a hot, sunny day, why does wearing a white shirt keep you cooler than wearing a black shirt made from the same material? (A) The material of the black shirt is thicker and makes the person feel hotter. (B) The black shirt absorbs more of the sun's energy, helping the person to feel cooler. (C) The white shirt reflects more of the sun's energy, helping the person to stay cooler. (D) Only "cool" people wear white shirts.

Short answer

(C) The white shirt reflects more of the sun's energy, helping the person to stay cooler.

Step-by-step solution

Understand the relationship between color and sunlight energy

Colors are perceptible due to their ability to absorb, transmit or reflect light. In this context, black absorbs all colors, absorbing most of the sunlight energy which increases temperature. White, on the other hand, reflects all colors, which means it reflects most of the sunlight energy, resulting in less heat absorption and thus a cooler temperature.

Analyze the options

Option (A) is incorrect because the thickness of the material doesn't change the way it absorbs or reflects light. Option (B) is incorrect because though a black shirt absorbs more energy, this won't make the person feel cooler, instead, it will make the person feel hotter. Option (D) is irrelevant to the science behind colors, light absorption, and reflection.

Formulate the correct answer

Option (C) is correct. Since a white shirt reflects more of the sunlight's energy, it won't absorb as much heat as a black shirt would, therefore a person wearing it will stay cooler. So, the correct answer is (C) The white shirt reflects more of the sun's energy, helping the person to stay cooler.

Key concepts

Light Absorption and Reflection

Understanding how light interacts with objects is essential for comprehending why certain colors affect temperature. When light strikes a surface, several phenomena can occur: absorption, reflection, and transmission. Absorption is when a material takes in the light energy, converting it to heat. Reflection is when the light bounces off the surface, and transmission is when light passes through a material.

Different colors absorb or reflect light differently. Darker colors, like black, absorb most of the wavelengths of light, thereby absorbing more energy and heating up more than lighter colors. On the contrary, lighter colors such as white reflect most of the light, which means they absorb less energy and remain cooler. This phenomenon is directly related to our everyday experiences, such as choosing appropriate clothing for the weather based on color to remain comfortable.

Color and Temperature

The color of an object not only affects its appearance but also its temperature when exposed to sunlight. This is due to the fact that colors are perceived based on the specific wavelengths of light that are absorbed or reflected by an object's surface. When all wavelengths are absorbed, we see black; when they're all reflected, we see white.

In the case of the white shirt in our exercise, its surface reflects the sunlight's spectrum, thus not increasing in temperature as much as a black shirt would. A black shirt absorbs almost all wavelengths, which means it will get hotter in the sunlight. This understanding of color and temperature is crucial in various fields, including fashion design, architecture, and even automotive industry, which use color to manage temperature control efficiently.

Energy and Heat Transfer

The concepts of energy and heat transfer are pivotal in explaining why a white shirt keeps you cooler than a black shirt on a hot day. Energy from the sun reaches us in the form of electromagnetic radiation, including visible light. When this energy is absorbed by an object, heat transfer occurs, warming the object. There are three methods of heat transfer: conduction, when heat moves through a substance; convection, the transfer of heat through a fluid such as air or water; and radiation, the transfer of heat through electromagnetic waves.

A white shirt reflects solar radiation, minimising heat absorption through radiation. Meanwhile, a black shirt, which absorbs this energy, undergoes a significant increase in temperature due to the energy conversion from light to heat. Hence, knowing how materials and colors interact with heat and energy can be a practical way to manage and control temperature in various scenarios.