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Showing posts from January, 2026

Sound – Class 9 Science Complete Notes

1. What is Sound? Sound is a form of energy which produces a sensation of hearing in our ears. Sound is produced by vibrating objects. Examples include vibrating tuning fork, vocal cords in humans, bells, musical instruments, etc. Vibration: Rapid to-and-fro (back and forth) motion of an object. Short Question: Can sound be produced without vibration? Answer: No, sound cannot be produced without vibration. 2. Medium of Sound The substance through which sound travels is called a medium . Sound can travel through solids, liquids, and gases but cannot travel through vacuum . Process of Sound Propagation: When an object vibrates, it makes the air particles around it vibrate. These air particles move back and forth from their original (rest) position. The vibrating air particles push nearby air particles. This causes the nearby particles to also start vibrating. In this way, vibrations pass from one particle to another. This process continues through the medi...

CBSE Starts Free Counselling Support for Class 10 & 12 Students (2026)

Free counselling support for class 10 and 12 students by CBSE A step by CBSE to reduce exam stress and support students emotionally. The Central Board of Secondary Education (CBSE) has launched a free psycho-social counselling service for Class 10 and Class 12 students and their parents. This service is specially started to help students deal with exam pressure, stress, and emotional challenges before board exams. Service Duration: 📅 Starts: 6 January 2026 📅 Ends: 1 June 2026 🎯 Covers the complete board exam period 🎯 Why Has CBSE Started This Support? To reduce exam fear and stress To help students stay confident To guide parents in supporting their children To promote healthy study habits 📞 How Can Students Use This Service? 1. Tele-Counselling 📞1800-11-8004 🌐 Hindi & English support 🕘 Monday to Friday ⏰ 9:30 AM – 5:30 PM 💬 Talk di...

CLASS 10 SCIENCE NOTES: CHAPTER - HEREDITY

HEREDITY 1. VARIATION Variation means differences among individuals of the same species . Examples: In a sugarcane field (asexual reproduction) → very little variation In humans (sexual reproduction) → large variation Key Points: Variations are less in asexual reproduction Variations are more in sexual reproduction Variations help organisms survive in changing environments Important: Variations produced during reproduction may be inherited and help in survival of species. 2. HEREDITY Heredity is the transfer of characters from parents to offspring. Inheritance: The process by which characters pass from one generation to another is called inheritance. 3. TRAITS Traits are characteristic features of an organism that can be: Physical → height, eye colour Physiological → blood group Acquired Traits Inherited Traits These traits develop during a person’s lifetime. These traits are present in a person since bi...