Buzz
The energy utilized for X-raying a fractured bone or heating food in a microwave isn't usually considered light, but it all falls under electromagnetic radiation. The human eye can only perceive a small segment of this spectrum, known as the visible spectrum, while the remainder remains unseen.
What Is the Visible Spectrum?
The visible spectrum, often referred to as the optical spectrum, represents the segment of the electromagnetic spectrum detectable by the human eye.
Spanning from radio waves with the longest wavelengths to gamma rays with the shortest, the electromagnetic spectrum includes microwaves, infrared light, visible light waves, ultraviolet light (UV light), and X-rays in between.
Within the visible light spectrum, red light possesses the longest wavelength, while violet light has the shortest. Shorter wavelengths correlate with higher frequencies and increased temperatures, enabling scientists to measure the temperature of stars in space using the visible light spectrum.
The sun emits a yellow glow and has a surface temperature of 10,000 degrees Fahrenheit. Cooler stars radiate a red hue, whereas hotter stars emit a violet color.
How Light Moves
Light travels in the form of waves or particles, though its visible behavior is best described through wave theory. These waves vary in size, measured by their wavelengths, which represent the distance between corresponding points on successive waves, such as from peak to peak or trough to trough.
The wavelengths visible to the human eye range between 400 and 700 billionths of a meter. Every color you perceive falls within this specific range.
However, waves can vary significantly in size, ranging from large radio waves to extremely small gamma rays. The visible light spectrum represents only a tiny fraction of the entire electromagnetic spectrum.
The Frequency of Light
Light waves are also quantified by their frequency, which refers to the number of waves passing a specific point within a set time frame. Frequency is measured in Hertz, abbreviated as Hz.
In the context of visible light, the human eye can detect frequencies ranging from 430 trillion Hz, perceived as red, to 750 trillion Hz, seen as violet. Frequencies beyond this range, whether higher or lower, remain invisible to the naked eye.
Visible light can also be assessed based on its energy content. All waves consist of traveling energy, with the energy level of each wave being directly proportional to its frequency. Higher energy corresponds to higher frequency, and lower energy to lower frequency.
In the visible light spectrum, violet, which has the highest frequency, also carries the greatest amount of energy. Conversely, red, with the lowest frequency, possesses the least energy.
