TeXes Science Practice Test

What type of radiation is emitted by the sun and reaches the Earth's surface as heat?

1. Visible light

2. Ultraviolet radiation

3. Infrared radiation

4. X-rays

The correct answer is: Infrared radiation

The correct answer is infrared radiation, which is a type of electromagnetic radiation that is primarily responsible for the heat we feel from the sun. While the sun emits a spectrum of radiation, including visible light and ultraviolet radiation, it is the infrared portion that plays a significant role in warming the Earth’s surface. Infrared radiation has wavelengths longer than visible light, which allows it to be perceived as heat. When this radiation reaches the Earth, it is absorbed by land and water, leading to an increase in temperature. This absorption process is crucial for maintaining the planet's climate and supporting life, as it contributes to the warmth necessary for various biological processes. Visible light, although important for vision and photosynthesis, does not have the same thermal effect as infrared radiation. Ultraviolet radiation, while a significant component of solar radiation, is mainly involved in processes like skin damage and the formation of vitamin D, rather than directly heating the Earth's surface. X-rays have much shorter wavelengths and higher energy than those necessary for contributing to the heat felt from the sun. They are not emitted in significant amounts by the sun in the context of heating the Earth's surface.