Question

Which of the following wavelength occurs in red part of the spectrum? (a) \(470 \mathrm{~nm}\) (b) \(390 \mathrm{~nm}\) (c) \(680 \mathrm{~nm}\) (d) \(830 \mathrm{~nm}\)

Short answer

The wavelength that occurs in the red part of the spectrum is (c) \(680 \mathrm{~nm}\).

Step-by-step solution

Identify the Range of Red Light

In the visible light spectrum, red light typically has a wavelength in the range of 625 nm to 740 nm.

Evaluate the Given Options

Now, evaluate the given options (a) \(470 \mathrm{nm}\), (b) \(390 \mathrm{nm}\), (c) \(680 \mathrm{nm}\), and (d) \(830 \mathrm{nm}\). We can see that options (a), (b) and (d) fall outside the 625 - 740 nm range. Thus, these options can be eliminated.

Select the Appropriate Option

Looking at the remaining option (c) \(680 \mathrm{nm}\), it falls within the range of red light (625 nm to 740 nm). Hence, this is the correct answer.

Key concepts

Visible Spectrum

The visible spectrum is the range of light that can be detected by the human eye. Light, although sometimes described as a wave, actually comprises many different colors, each associated with a specific wavelength range. The visible spectrum spans wavelengths from about 380 nanometers (nm) to 750 nm. This range allows humans to perceive light as various colors, from violet on the shortest end, through indigo, blue, green, yellow, and orange, to red on the longest end. Understanding these wavelengths is crucial in fields ranging from photography to physics, as each application may make use of different parts of the visible spectrum.

The way light is split into these colors is often demonstrated by the phenomenon of a rainbow or by using a prism. This separation of light is called dispersion. In many aspects of science and nature, recognizing how and why different colors appear can help us understand more about the materials and environments that produce them.

Red Light

Red light, a part of the visible spectrum, is well known for its warm, rich hue. It's defined by its wavelength, which stretches from approximately 625 nm to 740 nm. When we see red, it's because these longer wavelengths of light are being reflected into our eyes. Red light can be associated with various natural phenomena, like the reddish hues of a sunset, or artificial ones, such as the glow of neon signs.

Interestingly, red light has applications beyond just what we see. Due to its longer wavelength, it is less scattered by particles in the air, making it perfect for long-range visibility in conditions like fog or smoke. This is why brake lights and stop signs utilize red – to catch attention and effectively signal warnings. Red light's properties are leveraged in technology sectors, from astronomers using it to understand cosmic elements to dermatologists applying it in skin therapies due to its potential rejuvenating effects.

Nanometers (nm)

Nanometers (nm) is the unit of measurement used to describe wavelengths of light, including those in the visible spectrum. One nanometer is one-billionth of a meter, making it an exceptionally useful scale for measuring very small distances.

This unit is imperative in sciences like physics and chemistry, where the behavior of particles at a microscopic or quantum level is observed. In terms of light, understanding a wave's wavelength in nanometers allows scientists to determine its characteristics, like color and energy level. For instance, shorter wavelengths tend to have higher energy, such as ultraviolet or blue light, compared to longer wavelengths like red light.

Nanometer measurements play a significant role not just in scientific research, but also in technology industries that require precision control, such as in the manufacture of electronic components and the design of optical devices. By relating wavelengths with colors and energy, nanometers help us make sense of both the seen and unseen elements of the universe.