Energy > Energy and forces > Electromagnetic radiation and radiant energy
Electromagnetic radiation (light) is electromagnetic waves that propagate through space. There are many types of these waves depending on the frequency (X-rays, Ultraviolet, Visible light, Infrared etc). Radiant energy is the energy of electromagnetic waves.
Connection to Big Idea about forces: When a surface is exposed to electromagnetic radiation, photons interact with that surface (causing what we call) radiation’s pressure) and thus a force acts on it. An example of such an interaction are the tails of comets which always have a direction opposite to the Sun due to its radiation pressure.
Connection to Big Idea about the universe: Stars and galaxies throughout the Universe emit electromagnetic radiation at different wavelengths. Electromagnetic radiation is the only mean we have so far to collect information from the universe. Currently scientists are looking for ways to detect other types of radiant energy like neutrinos and gravitational waves which will change radically the way we perceive our universe.
Connection to Big Idea about particles: Electromagnetic radiation is carried by particles called photons. Subatomic particles interact with each other emitting electromagnetic radiation. Atoms and molecules can absorb electromagnetic radiation which increases their kinetic energy. Thus, they can become ionized or interact with each other.
Connection to Big Idea about quantum: When light is shed onto a material, its particles will interact with the incoming photons and emit electrons (photoelectric effect). Light is carried in discrete quanta packets (photons).
Connection to Big Idea about evolution: Light intensity and availability has a substantial influence on biodiversity as it is essential for many processes (like photosynthesis). High energy electromagnetic radiation (eg. UV and X-rays) however, can be harmful as it can cause changes to the DNA of living organisms.
Connection to Big Idea about the cell: Cells can absorb electromagnetic radiation (and thus energy) coming from the Sun to perform processes essential for their survival (like the synthesis of vitamin D in humans or converting dioxide and water into glucose and oxygen in plants). Excessive exposure to electromagnetic radiation (coming for example from cell phones) can however destroy cells due to the high increase of their temperature.
Connection to Big Idea about Earth: A lot of electromagnetic radiation is absorbed by the Earth’s atmosphere (gamma rays, x-rays and some ultraviolet and infrared). However, some reaches the Earth’s surface (optical, light, microwaves and some ultraviolet and infrared). This block of very energetic radiation such as the UV and X-ray radiation from the atmosphere is crucial for life on Earth.
Subjects related: Environmental Sciences, Physics
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