Overview
This lecture explains the electromagnetic spectrum, its regions, and the properties of visible light and other electromagnetic waves.
The Electromagnetic Spectrum
- The electromagnetic spectrum is the range of all frequencies or wavelengths of electromagnetic radiation.
- The spectrum is divided into regions: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays (from longest to shortest wavelength).
- Radio waves have the longest wavelength, lowest frequency, and lowest energy.
- Gamma rays have the shortest wavelength, highest frequency, and highest energy.
- Moving from radio waves to gamma rays: wavelength decreases, frequency and energy increase.
Visible Light Region
- Visible light is a small region within the electromagnetic spectrum that humans can see.
- Colors of visible light (in order): red, orange, yellow, green, blue, indigo, violet.
- Red light has the longest wavelength, lowest frequency, and lowest energy among visible colors.
- Violet light has the shortest wavelength, highest frequency, and highest energy among visible colors.
- Across visible light, as you move from red to violet, wavelength shortens and both energy and frequency increase.
Key Terms & Definitions
- Electromagnetic spectrum — the full range of electromagnetic wave frequencies or wavelengths.
- Wavelength — the distance between two consecutive peaks of a wave.
- Frequency — the number of wave cycles passing a point per second.
- Energy (of a wave) — related to the frequency; higher frequency means higher energy.
Action Items / Next Steps
- Review the regions of the electromagnetic spectrum and their order.
- Memorize the sequence of visible light colors and their properties.