Wavelength Of Red Light

Red Light Wavelength Range:

\[ \lambda \approx 620\text{–}750 \text{ nm} \]

Wavelength Range:

Red light wavelengths are defined by their position in the visible spectrum and do not require calculation.

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1. What Is The Wavelength Of Red Light?

Red light occupies the longest wavelength region of the visible spectrum, typically ranging from approximately 620 to 750 nanometers (nm). This range represents the boundary between visible light and infrared radiation.

2. The Visible Spectrum

The visible spectrum spans wavelengths from about 380 nm (violet) to 750 nm (red), with red light representing the longest wavelengths that human eyes can perceive.

\[ \text{Visible Spectrum} = 380\text{–}750 \text{ nm} \]

Where:

Violet: 380–450 nm
Blue: 450–495 nm
Green: 495–570 nm
Yellow: 570–590 nm
Orange: 590–620 nm
Red: 620–750 nm

3. Characteristics Of Red Light

Details: Red light has the lowest frequency and energy among visible colors. It experiences the least scattering in the atmosphere, which is why sunsets appear red and why red is used for warning lights and signals.

4. Applications Of Red Light

Applications: Red light is used in photography darkrooms, astronomy observation, medical therapies, traffic signals, and optical communications. Its long wavelength allows it to penetrate fog and haze better than shorter wavelengths.

5. Frequently Asked Questions (FAQ)

Q1: Why does red light have the longest wavelength?
A: In the visible spectrum, red light has the lowest frequency, which corresponds to the longest wavelength according to the relationship \( c = \lambda \nu \), where c is the speed of light.

Q2: Can humans see beyond 750 nm?
A: No, wavelengths longer than 750 nm are infrared radiation, which is invisible to the human eye but can be detected as heat.

Q3: Why is red used for stop signs and danger signals?
A: Red light scatters less in the atmosphere and is more visible at long distances, making it ideal for warning signals. It also has strong cultural associations with danger and stopping.

Q4: How does red light affect human physiology?
A: Red light therapy is used for various treatments including skin rejuvenation, wound healing, and pain relief. It's also known to have less disruptive effects on night vision compared to other colors.

Q5: Is the red light wavelength range the same for all people?
A: While the general range is consistent, individual perception may vary slightly. Color blindness, particularly protanopia, can affect how individuals perceive red light.