Problem 22 - Chemistry The Science in Context

Question

In each pair, which radiation has longer wavelength? (a) visible light or microwaves; (b) radio waves or gamma rays; (c) infrared or ultraviolet radiation

Step-by-Step Solution

Answer

Answer: (a) Microwaves, (b) Radio waves, (c) Infrared radiation.

Step 1: Pair (a) Visible light or Microwaves

In the order of the electromagnetic spectrum, Microwaves come before Visible light. So, Microwaves have a longer wavelength compared to Visible light.

Step 2: Pair (b) Radio waves or Gamma rays

In the order of the electromagnetic spectrum, Radio waves come before Gamma rays. So, Radio waves have a longer wavelength compared to Gamma rays.

Step 3: Pair (c) Infrared or Ultraviolet radiation

In the order of the electromagnetic spectrum, Infrared radiation comes before Ultraviolet radiation. So, Infrared radiation has a longer wavelength compared to Ultraviolet radiation.

Key Concepts

Wavelength Comparison

Understanding the electromagnetic spectrum is pivotal for exploring the nature of different types of radiation. Wavelength, which measures the distance between successive peaks of a wave, is a key characteristic in distinguishing among various types of electromagnetic radiation.

Longer wavelengths are associated with lower frequencies and energies, whereas shorter wavelengths correspond to higher frequencies and energies. The spectrum ranges from long-wavelength radio waves to short-wavelength gamma rays, with microwaves, infrared, visible light, and ultraviolet radiation positioned in between. Knowledge of this order is essential for comparing wavelengths and can be remembered by the mnemonic 'Raging Martians Invaded Venus Using X-ray Guns', standing for Radio, Microwaves, Infrared, Visible, Ultraviolet, X-rays, and Gamma rays.

This relationship is crucial across numerous applications including communication, medical imaging, and our understanding of the universe.

Visible Light vs Microwaves

When comparing visible light and microwaves, it's important to recognize their positions in our everyday lives. Visible light is the range of electromagnetic radiation that the human eye can detect, which allows us to see the world around us. It has shorter wavelengths ranging from about 380 to 750 nanometers (m).On the other hand, microwaves, which are typically used in cooking and wireless communications, have much longer wavelengths, from 1 millimeter to 1 meter (m). The longer wavelengths enable microwaves to penetrate through substances, heating up water molecules effectively in food and traversing the atmosphere for satellite communications.

Thus, in comparison, microwaves have longer wavelengths than visible light, meaning they have lower frequencies and energies but greater ability for certain types of penetration.

Radio Waves vs Gamma Rays

Radio waves and gamma rays sit at opposite ends of the electromagnetic spectrum, encompassing vastly different wavelengths and, consequently, energies. Radio waves, used in broadcasting and communication, possess the longest wavelengths in the electromagnetic spectrum, which can range from a millimeter to over 100 kilometers (m). These extended wavelengths enable them to travel long distances and around obstacles, making them ideal for communication purposes.

In stark contrast, gamma rays have the shortest wavelengths, less than 10 picometers (m), and the highest energies. These penetrating rays, which result from nuclear reactions and certain astrophysical processes, are used in applications such as cancer treatment through radiotherapy, and they also pose a great threat to living cells due to their high energy. This distinction underscores the vast diversity in the uses and properties of electromagnetic waves across the spectrum.

Infrared vs Ultraviolet Radiation

Infrared and ultraviolet radiation are neighboring bands that flank visible light on the electromagnetic spectrum. Infrared radiation, with longer wavelengths than visible light, ranges from 700 nanometers to 1 millimeter (m). These wavelengths impart warmth, which is why infrared is often used in heating applications and thermal imaging. A fascinating fact about infrared radiation is that we experience it daily as the heat we feel from the Sun, without being able to visually perceive it.

Conversely, ultraviolet radiation has shorter wavelengths than visible light, ranging from 10 to 380 nanometers (m). Ultraviolet rays are known for their ability to induce a suntan or sunburn as they possess enough energy to cause molecular changes in skin cells. In higher doses, ultraviolet radiation can be harmful, but it is also harnessed in sterilization processes and in producing vitamin D within the skin. This knowledge about the differing properties of infrared and ultraviolet radiation is important for their safe and effective application in various technologies and understanding their effects on health and the environment.