Problem 21 - Chemistry The Science in Context

Question

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

Step-by-Step Solution

Answer

Provide your answer for each comparison.

Step 1: (a) Ultraviolet or infrared radiation comparison

In comparing ultraviolet and infrared radiation, ultraviolet radiation is further along in the electromagnetic spectrum (closer to gamma rays) and therefore has a higher frequency compared to infrared radiation. Answer: Ultraviolet has a higher frequency.

Step 2: (b) Visible light or gamma rays comparison

When comparing visible light and gamma rays, gamma rays are at the highest frequency end of the electromagnetic spectrum, making it have a higher frequency than visible light. Answer: Gamma rays have a higher frequency.

Step 3: (c) Microwaves or radio waves comparison

In the comparison between microwaves and radio waves, microwaves are further along (closer to gamma rays) in the electromagnetic spectrum. Thus, microwaves have a higher frequency than radio waves. Answer: Microwaves have a higher frequency.

Key Concepts

Frequency Comparison

Frequency is a measure of how many waves pass a point in one second. It's an important concept in understanding the electromagnetic spectrum. The electromagnetic spectrum is a range of all types of electromagnetic radiation, characterized by frequency or wavelength.

• Higher frequency means more waves pass per second.
• The electromagnetic spectrum ranges from low frequencies like radio waves to high frequencies such as gamma rays.
• Comparing frequencies allows us to understand energy levels and applications of different radiations.

For instance, when comparing ultraviolet and infrared radiation, ultraviolet has a higher frequency because it is closer to the high-energy gamma rays on the spectrum. This means it has more energy than infrared radiation. Higher frequency often correlates with higher energy, making the comparison crucial in applications like UV sterilization or infrared heating.

Ultraviolet Radiation

Ultraviolet (UV) radiation is a type of electromagnetic radiation that lies just beyond the visible spectrum. It ranges from approximately 10 nm to 400 nm in wavelength, which means higher frequency than infrared light.

• UV radiation is divided into three types: UVA, UVB, and UVC.
• UVC has the highest frequency and is mostly absorbed by the Earth's atmosphere.
• UVB and UVA are responsible for effects like skin tanning and risk of sunburn.

Since UV radiation has a higher frequency than infrared, it's used in a variety of applications including sterilization and disinfection. However, prolonged exposure can damage living tissue, which is why sunscreen is important for protection.

Gamma Rays

Gamma rays are the highest-frequency electromagnetic waves and have the shortest wavelength in the electromagnetic spectrum. They occur at frequencies above 10 exahertz (EHz), making them incredibly energetic and powerful.

• Gamma rays are produced by atomic nuclei transitions and certain kinds of radioactive decay.
• Due to their high energy, they can penetrate most materials, requiring thick lead or concrete for shielding.
• Commonly used in medicine for cancer treatment and imaging.

The comparison between gamma rays and visible light clearly shows that gamma rays have a far higher frequency and consequently, energy. Their properties make them valuable yet dangerous, necessitating precautions when handled.

Microwaves

Microwaves, located between radio waves and infrared on the electromagnetic spectrum, have frequencies ranging from about 300 MHz to 300 GHz. They possess higher frequencies compared to radio waves but lower frequencies than infrared.

• Microwaves are highly effective for communication and cooking, as they interact with water molecules to heat food.
• They are also essential in radar technology and satellite communications.
• Their frequency allows them to penetrate the atmosphere, making them useful for space exploration.

When compared to radio waves, microwaves have higher frequencies, meaning they can transmit more data and are better suited for high-speed communications. This property is why they are crucial in modern technology, from Wi-Fi to cell phones.