Problem 2201 - JEE Physics

Question

Which of the following electromagnetic wave has the least frequency? (A) radiowave (B) infrared radiation (C) microwave (D) x rays

Step-by-Step Solution

Answer

The electromagnetic wave with the least frequency among the given options is (A) radiowave.

Step 1: Recall the order of electromagnetic waves in the spectrum

The order of the different types of electromagnetic waves, from lowest to highest frequency, is as follows: 1. Radio waves 2. Microwaves 3. Infrared radiation 4. Visible light 5. Ultraviolet radiation 6. X-rays 7. Gamma rays Keep in mind that as we move from left to right in this order, the frequency of the electromagnetic waves increases.

Step 2: Compare the frequencies of the given options

Based on the order mentioned in Step 1, let's determine the position of each option in the electromagnetic spectrum: (A) Radiowave - Position 1 (lowest frequency) (B) Infrared radiation - Position 3 (C) Microwave - Position 2 (D) X rays - Position 6 (higher frequency)

Step 3: Identify the electromagnetic wave with the least frequency

From the comparisons in Step 2, it is evident that radiowaves (A) have the lowest frequency among the given options. So, the correct answer is (A) radiowave.

Key Concepts

Radio Waves

Radio waves are a type of electromagnetic wave found at the far left of the electromagnetic spectrum, signifying that they have the lowest frequency among all electromagnetic waves listed, such as microwaves and x-rays. These waves are extensively used for communication purposes because they can travel long distances without losing strength.

Radio waves are all around us. For instance:

• Television broadcasts rely on radio waves to transmit signals from broadcasting stations to your television set.
• Radios in your car or home receive radio wave signals from radio stations, which are then converted into the sound that you hear.
• Mobile phones use specific frequencies of radio waves to communicate with cell towers and relay signals across the network.

These characteristics make radio waves vital in modern communication technology. They are efficient at penetrating through buildings and traveling over vast distances, making them ideal for transmitting information across nations or even continents.

Frequency Comparison

When comparing frequencies between different types of electromagnetic waves, it's important to understand that frequency indicates the number of cycles a wave completes in one second. More cycles mean a higher frequency and vice versa.

In the electromagnetic spectrum, waves with higher frequencies like x-rays and gamma rays carry more energy, which allows them to penetrate materials that lower frequency waves cannot. However, these waves can also be more harmful to living organisms.

Here's a simple comparison of the given electromagnetic waves based on frequency:

• Radio Waves: Lowest frequency; used mainly for communication.
• Microwaves: Higher frequency than radio waves, used in cooking and satellite communication.
• Infrared Radiation: More frequency than microwaves, often experienced as heat.
• X-rays: Significantly higher frequency, used in medical imaging to see through soft tissue.

Knowing the different frequencies helps in identifying their various applications and potential risks when exposed to living organisms.

Types of Electromagnetic Waves

The electromagnetic spectrum is vast, comprising various types of waves, each with distinct characteristics. These include radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, x-rays, and gamma rays, listed in order of increasing frequency.

Each type of wave has unique properties:

• Radio Waves: Extremely low in frequency; used broadly in communication technologies such as radio and TV broadcasting.
• Microwaves: These have applications in cooking and satellite transmissions due to their ability to heat substances and transmit data.
• Infrared Radiation: Often felt as heat; used in heaters, remote controls, and thermal imaging.
• Visible Light: The only part of the spectrum visible to the human eye, responsible for the colors we see in the world around us.
• Ultraviolet Radiation: Beyond visible light; used in sterilization and in producing vitamin D in the skin.
• X-rays: High-frequency waves used in medical diagnostics to visualize bone structures.
• Gamma Rays: Possess the highest frequencies; used in cancer treatment and emitted by radioactive substances.

Understanding these types of electromagnetic waves is crucial for their diverse practical applications, as well as for recognizing the safety measures needed when exposed to higher frequency waves.