Light and the electromagnetic spectrum Study Guide

The electromagnetic spectrum encompasses a vast range of radiation, from very long radio waves to extremely short gamma rays. While theoretically infinite, the spectrum is often divided into distinct regions based on frequency (and corresponding wavelength). Our eyes, however, are biological instruments with inherent limitations. They are only sensitive to a very narrow band of this expansive spectrum, which we perceive as visible light. This visible spectrum runs from red light, which has the lowest frequency (and longest wavelength) within this range, through orange, yellow, green, blue, and indigo, ending with violet light, which has the highest frequency (and shortest wavelength) that humans can detect. Radiation outside this specific frequency range, such as infrared or ultraviolet, is invisible to the human eye, even though it is still part of the electromagnetic spectrum and has various effects and applications.

Changes within atoms and atomic nuclei are fundamental processes in physics that can both generate and be caused by electromagnetic radiation. When electrons within an atom move from a higher energy level to a lower one, or when atomic nuclei undergo decay or fusion, they emit energy in the form of electromagnetic radiation. This radiation can span a broad spectrum of frequencies, including visible light, X-rays, and gamma rays, depending on the energy involved in the transition. Conversely, atoms and nuclei can absorb electromagnetic radiation. When an atom absorbs a photon with sufficient energy, an electron can jump to a higher energy level. When a nucleus absorbs a high-energy photon or particle, it can become unstable, potentially leading to nuclear reactions or changes in its state.