IntroductionWaves and Sound form an important and interesting part of Physics. In this chapter, we study how energy travels in the form of waves and how sound is produced, transmitted, and heard. Topics such as types of waves, characteristics of sound (pitch, loudness, and quality), echo, and basic wave motion help build a strong conceptual … Read more
Introduction The human eye is one of the most important sense organs, which enables us to see the beautiful and colourful world around us. It works like a natural camera by allowing light to enter, forming an image on the retina, and sending signals to the brain. The study of the human eye helps us … Read more
Refraction of light is the phenomenon in which the path of light changes when it travels from one medium to another due to a change in its speed. This concept helps us understand many natural and practical effects such as the bending of a pencil in water, formation of images by lenses, and working of … Read more
Introduction Reflection of Light is one of the fundamental topics of Optics and forms the base for understanding mirrors, image formation, and optical instruments. When light rays strike a smooth surface such as a mirror, they bounce back into the same medium; this phenomenon is known as reflection of light. The laws of reflection explain … Read more
Introduction Physics is the science of measurement, and every physical quantity must be expressed quantitatively. Units and Dimensions form the foundation of Physics, helping us measure, compare, and understand physical quantities accurately. In this chapter, we study different systems of units, fundamental and derived quantities, and the concept of dimensions, which are essential for analyzing … Read more
The NDA (National Defence Academy) and CDS (Combined Defence Services) exams test candidates on basic concepts of General Science, including foundational Chemistry. Although the questions are simple, they require clear understanding, quick recall, and conceptual clarity.Topics like Atomic Structure and Redox Reactions form the building blocks for many questions asked in General Science sections of … Read more
In Chemistry, many of the things we see around us—plastic bottles, rubber tyres, glass windows—are made from important materials that science has helped us create. Two such important concepts are Polymers and Glass. Understanding how they are formed and what they are used for gives students a strong foundation for higher studies and competitive exams … Read more
The NDA (National Defence Academy) & CDS (Combined Defence Services) exams are prestigious national-level examinations conducted for candidates who wish to join the Indian Armed Forces—Army, Navy, and Air Force. For students starting early (Class 6 and above), building a strong foundation in Science, Maths, and General Knowledge is extremely helpful. Learning topics like the … Read more
The NDA CDS 1 2026 examination tests candidates on conceptual clarity and application-based understanding of General Science topics, including Chemistry. In Chemistry, questions are generally fact-based, conceptual, and MCQ-oriented, covering fundamental themes from Class 9–12 NCERT. Topics like Polymers and Cement Preparation are commonly included because they deal with practical, real-life applications of chemical principles. … Read more
The NDA CDS 1 2026 examination tests candidates on fundamental concepts of General Science, including essential Chemistry topics. Understanding Redox Reactions and Carbon and its Compounds is crucial, as these topics frequently appear in multiple-choice questions. Mastering the concepts, common definitions, and applications will help improve accuracy and speed during the exam. In today’s Class-4 … Read more
