Problem 2147 - JEE Physics

Question

The waves used in communication are generally called (A) \(\gamma\) rays (B) \(\alpha\) rays (C) microwaves (D) radiowaves

Step-by-Step Solution

Answer

Among the given options, microwaves (\(C\)) are the most commonly used waves in communication systems due to their ability to penetrate through obstacles and travel long distances.

Step 1: Understand the given options

To determine which type of waves are used in communication, let's first understand what each option represents: (A) \(\gamma\) rays are a form of ionizing radiation, meaning they have the potential to damage human tissue and electronic components. They are not used in communication because of their destructive nature. (B) \(\alpha\) rays are particles (helium nuclei) that are also ionizing radiation. Due to the penetration capacity of \(\alpha\) rays, they are also not used in communication. (C) Microwaves are a form of non-ionizing radiation. They have a frequency range of 300 MHz to 300 GHz and are commonly used for communication because they can penetrate through obstacles and travel long distances. (D) Radiowaves have a lower frequency range than microwaves, which is 3 kHz to 300 GHz, and are a form of non-ionizing radiation. They are used for communication, especially in radio and television broadcasts, but not as commonly as microwaves for all types of communication systems.

Step 2: Select the correct answer

Since we investigated all options, we can now identify the correct answer. In communication systems, microwaves are commonly used because of their ability to easily penetrate through obstacles and travel long distances. Therefore, the correct answer is: (C) microwaves

Key Concepts

Gamma Rays

Gamma rays are a type of electromagnetic wave that is highly energetic. They are characterized by having the shortest wavelengths and the highest frequencies among all electromagnetic waves. This gives them the ability to penetrate substances more deeply than others, making them extremely potent and ionizing.

• Source of Gamma Rays: These rays are typically emitted by radioactive substances and certain astronomical sources such as pulsars, neutron stars, and supernovae.
• Applications: While not used in communication, gamma rays have important applications in medicine, such as cancer treatment, and in industries for material inspection.
• Risks: Due to their ionizing nature, gamma rays are dangerous and can cause severe damage to biological tissues, leading to radiation sickness or increased cancer risk.

Because of these properties, gamma rays are not suitable for communication, as they would disrupt electronic systems and biological organisms.

Alpha Rays

Alpha rays consist of alpha particles, which are essentially helium nuclei made up of two protons and two neutrons. Unlike electromagnetic waves, they are a form of particulate radiation.

• Characteristics: Alpha rays have a relatively large mass and are positively charged, which limits their ability to penetrate substances.
• Uses: They are used in smoke detectors and for certain industrial applications, like gauging the thickness of materials.
• Health Impact: Although they cannot penetrate skin, if ingested or inhaled, they can cause significant damage to human tissues due to their ionizing property.

While alpha rays play some beneficial roles in industry and safety devices, they are unsuitable for communication due to their limited range and ionizing nature.

Microwaves

Microwaves are a subset of the electromagnetic spectrum and are critical to modern communication technology. They sit between radiowaves and infrared waves on the spectrum, with wavelengths ranging from about one meter to one millimeter and frequencies between 300 MHz and 300 GHz.

• Applications: Microwaves are extensively used in communication systems such as cellular networks, Wi-Fi, satellite transmissions, and radar technologies.
• Advantages: Their ability to pass through the atmosphere and across long distances, coupled with the capacity to carry high data rates, makes them preferable for many communication purposes.
• Safety: As non-ionizing radiation, microwaves are generally safe for human exposure at controlled intensities. However, high exposure levels can generate heat, which must be carefully managed.

Microwaves stand out as a primary choice for communication waves due to these advantageous properties, making them indispensable in daily life and technology.

Radiowaves

Radiowaves are the largest segment of the electromagnetic spectrum, characterized by their low frequency and long wavelengths, typically ranging from 3 kHz to 300 GHz. They were among the first types of waves harnessed for communication.

• Communications Use: These waves are omnipresent in radio and television broadcasting, satellite communications, and wireless networks.
• Advantages: Radiowaves can travel long distances and penetrate walls, making them ideal for broadcasting and transmission of audio, video, and data signals over extended ranges.
• Accessibility: Because of their lower energy, radiowaves are considered safe for everyday exposure, and infrastructure for their usage is widely available.

Despite having a lower carrying capacity for data compared to microwaves, radiowaves remain integral to global communication systems due to their reliability and reach.