Dr Ravi P Agrahari, Ph.D. from IIT Delhi, is a distinguished scholar with extensive experience in Energy, Environment Science, and Science & Technology. He has authored numerous books for UPSC examinations and is renowned for his teaching expertise, having mentored UPSC aspirants for over two decades across 50 prestigious coaching institutes in 15 states in India. Recipient of Junior and Senior Research Fellowships from CSIR, Government of India, Dr. Agrahari served as a research scientist at IIT Delhi from 2015 to 2017. Currently, he serves as an independent consultant at the Bag Energy Research Society, Varanasi, focusing on Environment, Renewable and Sustainable Energy, and Biogas issues. Passionate about education, he collaborates with NGOs and Civil Societies to provide quality education to economically disadvantaged students. Connect with him on Telegram at [https://t.me/drravipagrahari] for expert guidance on UPSC examinations.