Nios Class 12th physics Chapter 1st
Introduction
Since ancient times, human beings have always been curious to understand the mysteries of nature. The shining stars in the sky, sunrise and sunset, rainfall, lightning, sound, and the falling of objects inspired humans to think deeply about the natural world. The study and understanding of these natural phenomena gave birth to Physics.
Today’s modern age is the age of science and technology. Mobile phones, the internet, computers, satellites, airplanes, medical instruments, electricity, robotics, and space science are all based on the principles of Physics.
Physics is not just a subject of books; it is the foundation of our daily life. Every object and technology we use in our surroundings is connected to some principle of Physics.
🌍 What is Physics?
The word Physics is derived from the Greek word Fusis, which means “Nature.”
Physics is the branch of natural science that deals with the study of matter, energy, force, motion, and natural phenomena.
Simple Definition of Physics
“Physics is the scientific study of nature and natural phenomena.”
Physics helps us understand:
- Why objects fall toward the Earth
- Why planets revolve around the Sun
- How electricity is produced
- How light travels
- How sound is heard
- How magnets work
🔬 What is Science?
The word Science comes from the Latin word Scientia, which means “to know.”
When humans observe nature, perform experiments, and try to understand the reasons behind natural events, it is called science.
Characteristics of Science
- Science is based on logic
- Science is supported by experiments
- Science continuously develops
- No scientific theory is considered final forever
⚛️ Matter
Anything:
- That has mass
- Occupies space
- Can be experienced directly or indirectly
is called matter.
Examples
- Water
- Air
- Stone
- Iron
- Gold
- Electron
- Atom
⚡ Energy
The capacity to do work is called energy.
No work can be performed without energy.
Types of Energy
- Heat Energy
- Light Energy
- Electrical Energy
- Sound Energy
- Nuclear Energy
- Chemical Energy
-
Nios Class 12th physics Chapter 1st
🌟 Relationship Between Mass and Energy
Earlier, scientists believed that matter and energy were completely different, but Albert Einstein proved that matter and energy can be converted into each other.
This relation is expressed by the formula:
E=mc2E=mc^2
Where:
- EE = Energy
- mm = Mass
- cc = Speed of Light
This theory forms the basis of nuclear energy and solar energy.
🚀 Scope of Physics
The scope of Physics is extremely vast. It studies everything from microscopic particles to the gigantic universe.
Physics is mainly divided into two parts:
1. Macroscopic Physics
It deals with large objects and everyday phenomena.
Examples:
- Motion of planets
- Movement of vehicles
- Working of machines
- Construction of bridges
2. Microscopic Physics
It deals with extremely small particles and atomic phenomena.
Examples:
- Atoms
- Electrons
- Neutrons
- Nuclear reactions
📚 Major Branches of Physics
1. Mechanics
This branch deals with motion, force, and energy.
Main Topics
- Newton’s Laws of Motion
- Gravitation
- Work and Energy
- Momentum
Important Formula
v=u+atv=u+at
2. Thermodynamics
This branch studies heat and transformation of energy.
Applications
- Engines
- Refrigerators
- Air Conditioners
3. Optics
The study of light and related phenomena is called Optics.
Main Topics
- Reflection
- Refraction
- Diffraction
- Rainbow Formation
4. Electrodynamics
This branch studies electricity and magnetism.
Applications
- Electric Motors
- Generators
- Transformers
- Radio Systems
5. Oscillations and Waves
This branch deals with vibrations and waves.
Examples
- Sound Waves
- Musical Vibrations
- Radio Waves
6. Modern Physics
It is the most advanced branch of Physics.
Main Topics
- Quantum Theory
- Atomic Structure
- Nuclear Physics
- Semiconductors
🌈 Excitement of Physics
Physics is an exciting science because it reveals the hidden secrets of nature.
- Isaac Newton discovered the law of gravitation by observing a falling apple.
- Michael Faraday discovered electromagnetic induction.
- Galileo Galilei studied the oscillations of pendulums.
Modern technologies such as:
- Computers
- Mobile Phones
- Internet
- Satellites
- Robots
- Lasers
are all based on the principles of Physics.
🛰️ Physics, Technology, and Society
Physics has played a major role in the development of society and technology.
Contribution to Technology
- Airplanes
- Motor Cars
- Computers
- Mobile Phones
- Internet
- Satellite Communication
Contribution to Medical Science
- X-rays
- Ultrasound
- ECG
- CT Scan
- Laser Surgery
Contribution to Space Science
- Rockets
- Satellites
- Spacecraft
👨🔬 Great Physicists and Their Contributions
| Scientist | Contribution |
|---|---|
| Galileo Galilei | Law of Inertia |
| Isaac Newton | Laws of Motion |
| Albert Einstein | Theory of Relativity |
| Michael Faraday | Electromagnetic Induction |
| James Clerk Maxwell | Electromagnetic Theory |
| C. V. Raman | Raman Effect |
💥 Fundamental Forces in Nature
There are four fundamental forces in nature.
1. Gravitational Force
The attractive force between two masses is called gravitational force.
F=Gm1m2r2F=G\frac{m_1m_2}{r^2}
Characteristics
- Weakest force in nature
- Always attractive
- Acts over long distances
2. Electromagnetic Force
This force acts between charged particles.
Characteristics
- Can be attractive or repulsive
- Stronger than gravitational force
3. Strong Nuclear Force
This force binds protons and neutrons inside the nucleus.
4. Weak Nuclear Force
This force is responsible for radioactive decay.
📖 Conservation Laws
Law of Conservation of Energy
Energy can neither be created nor destroyed; it can only be transformed from one form to another.
Law of Conservation of Momentum
If no external force acts on a system, its total momentum remains constant.
Law of Conservation of Charge
The total electric charge of an isolated system always remains constant.
📝 Important Questions for Examination
Very Important Questions
- Define Physics.
- Differentiate between matter and energy.
- Explain the branches of Physics.
- Describe the role of Physics in society.
- Explain the fundamental forces of nature.
🎯 Conclusion
National Institute of Open Schooling Class 11 Physics Chapter “Physical World and Measurement” forms the foundation for understanding the basic concepts of science. This chapter helps students develop scientific thinking, understand the laws of nature, and build a strong base for advanced Physics topics.
Regular study and practice of concepts, formulas, and numerical problems from this chapter make future Physics chapters much easier to understand.