Phenomenon Used in Optical Fibre

Introduction

Optical fibres are widely used in telecommunications and networking due to their ability to transmit data over long distances with minimal loss. The core principle behind the functioning of optical fibres is based on a fundamental phenomenon in physics. Understanding this phenomenon is essential for grasping how optical fibres work and their applications in modern technology.

1. Total Internal Reflection

• Definition: The primary phenomenon used in optical fibres is Total Internal Reflection (TIR). Total internal reflection occurs when a wave traveling through a medium hits the boundary with a medium of lower refractive index at an angle greater than the critical angle. Instead of passing through, the wave is completely reflected back into the original medium.
• Critical Angle: The critical angle is the minimum angle of incidence at which total internal reflection occurs. It depends on the refractive indices of the two media involved. For light to be totally internally reflected, the angle of incidence must exceed this critical angle.
• Example: In optical fibres, the core of the fibre has a higher refractive index than the cladding surrounding it. Light signals traveling through the core are reflected back into the core due to total internal reflection, allowing the light to travel long distances with minimal loss.

2. Structure of Optical Fibres

• Core and Cladding: Optical fibres consist of two main parts:
  • Core: The central part of the fibre where light is transmitted. It has a higher refractive index.
  • Cladding: The outer layer surrounding the core with a lower refractive index. The cladding ensures that light is confined within the core by reflecting it back through total internal reflection.
• Example: A typical optical fibre might have a core made of silica with a refractive index of 1.45 and a cladding with a refractive index of 1.40. This difference ensures that light remains within the core due to total internal reflection.

3. Applications of Optical Fibres

• Telecommunications: Optical fibres are used extensively in telecommunications to transmit data over long distances with high bandwidth and low attenuation. The phenomenon of total internal reflection enables these fibres to carry signals with minimal signal degradation.
  • Example: Undersea fibre optic cables, such as the MAREA cable connecting the U.S. to Spain, use total internal reflection to transmit terabits of data per second across thousands of kilometers.
• Medical Imaging: Optical fibres are employed in medical endoscopy to transmit light and images from inside the body to external monitors. The fibres use total internal reflection to deliver clear and high-resolution images.
  • Example: The use of optical fibres in laparoscopes allows surgeons to view and operate on internal organs with minimal invasiveness.
• Networking and Data Centres: In data centres and high-speed networks, optical fibres facilitate rapid data transfer between servers and storage devices. The efficiency of total internal reflection is crucial for maintaining the integrity and speed of data transmission.
  • Example: Google’s data centres use optical fibre networks to connect servers and manage massive amounts of data efficiently.

4. Advantages of Optical Fibres

• High Bandwidth: Optical fibres provide significantly higher bandwidth compared to traditional copper cables, allowing for the transmission of vast amounts of data.
  • Example: The implementation of Dense Wavelength Division Multiplexing (DWDM) technology in optical fibres can increase data capacity by combining multiple signals on different wavelengths.
• Low Signal Loss: The use of total internal reflection minimizes signal loss and attenuation over long distances, making optical fibres ideal for long-haul communication.
  • Example: Optical fibres used in long-distance communication links experience much less signal degradation compared to copper cables.
• Immunity to Electromagnetic Interference: Optical fibres are not affected by electromagnetic interference, which is common in electrical cables. This property ensures stable and reliable data transmission.
  • Example: Optical fibres are preferred for environments with high electromagnetic interference, such as industrial settings or medical facilities.

Conclusion

The phenomenon of Total Internal Reflection is the fundamental principle behind the operation of optical fibres. This principle enables the transmission of light through the core of the fibre with minimal loss, making optical fibres essential for modern telecommunications, medical imaging, and high-speed networking. Understanding this phenomenon is crucial for UPSC Mains aspirants to appreciate the technological advancements in communication and data transfer.

भारत के नियंत्रक एवं महालेखा परीक्षक (CAG) की संवैधानिक स्थिति

1. नियुक्ति और कार्यकाल: CAG की नियुक्ति राष्ट्रपति द्वारा की जाती है, और इसका कार्यकाल नियंत्रक और महालेखा परीक्षक अधिनियम, 1971 के तहत निर्धारित होता है। कार्यकाल 65 वर्ष की आयु तक होता है। गिरीश चंद्र मुर्मू 2020 में हाल ही में नियुक्त CAG हैं।

2. स्वतंत्रता: CAG पूरी स्वतंत्रता से कार्य करता है और इसके पद की सुरक्षा सुनिश्चित की जाती है। हटाने की प्रक्रिया सर्वोच्च न्यायालय के न्यायाधीश की तरह होती है, जो इसकी स्वतंत्रता को बनाए रखती है।

3. अधिकार और कार्य: CAG केंद्र और राज्य सरकारों के खातों की लेखा परीक्षा करता है। इसके रिपोर्ट संसद और राज्य विधानसभाओं में प्रस्तुत किए जाते हैं। उदाहरण के लिए, 2021 की CAG रिपोर्ट ने कोविड-19 टीकाकरण प्रक्रिया में अनियमितताओं को उजागर किया।

निष्कर्ष: CAG की संवैधानिक स्थिति उसे स्वतंत्र रूप से काम करने और सरकारी वित्तीय पारदर्शिता सुनिश्चित करने की शक्ति देती है।

Differences Between the Indian Federal System and the U.S. Federal System

1. Nature of Federalism:

• India: India has a quasi-federal system with a strong central government. The Union Government has significant powers over states, and in case of a conflict, the Union prevails. For example, the Article 356 allows the central government to dissolve state assemblies and impose President’s rule.
• USA: The U.S. follows a dual federalism model where states have substantial autonomy. The 10th Amendment reserves powers not explicitly given to the federal government to the states.

2. Division of Powers:

• India: The Union List, State List, and Concurrent List divide powers, but in case of conflict, Union laws prevail.
• USA: Powers are divided between the federal government and states without a concurrent list, providing clearer separation.

3. Judicial Review:

• India: The Supreme Court has the power to review and adjudicate conflicts between state and central laws.
• USA: The Supreme Court can also review and resolve federal-state conflicts, but the principle of states’ rights often limits federal intervention.

Conclusion: India’s federal system is more centralized compared to the U.S., with greater central authority and overlapping powers between central and state governments.

Contribution of the Indian Diaspora Towards Economic Structure in India

1. Investment and Remittances: The Indian diaspora significantly contributes through foreign direct investments (FDI) and remittances. For example, Indian-Americans have invested in various sectors, boosting India’s startup ecosystem. Additionally, remittances from the diaspora have been vital in supporting rural and urban economies.

2. Skill Transfer and Entrepreneurship: Diaspora members bring back expertise and innovation. Notable is the role of NRIs in setting up tech startups and manufacturing units in India, like the investments by Nandan Nilekani and Sundar Pichai in technology sectors.

3. Philanthropy and Development Projects: The diaspora’s philanthropic efforts support numerous development projects. For instance, Ratan Tata’s contributions to educational institutions and healthcare facilities demonstrate their impact on India’s social infrastructure.

Conclusion: The Indian diaspora plays a crucial role in shaping India’s economic landscape through investment, skill transfer, and philanthropy.

Impact of Self-Help Groups (SHGs) on India’s Rural Life

1. Economic Empowerment: SHGs have significantly boosted rural incomes by providing members with access to microfinance. For instance, the National Rural Employment Guarantee Act (NREGA) has been supplemented by SHGs to support income generation activities like agriculture and small enterprises.

2. Women’s Empowerment: SHGs have been instrumental in empowering women by promoting their participation in economic activities and decision-making processes. The Deendayal Antyodaya Yojana (DAY-NRLM) has helped SHGs in increasing women’s social and economic status.

3. Social Development: SHGs foster community solidarity and collective action, addressing local issues such as healthcare and education. For example, SHGs in Tamil Nadu have successfully undertaken projects for sanitation and literacy.

Conclusion: SHGs have positively transformed rural India by enhancing economic opportunities, empowering women, and fostering community development.