NCERT Class 11 Physics Chapter 13: Oscillations PDF Download Free

Chapter 13 of Class 11 Physics, Oscillations, deals with the study of repetitive motions in systems like pendulums, springs, and sound waves. It introduces key terms like amplitude, time period, frequency, and phase, and builds a solid foundation for understanding harmonic motion. Oscillations are seen everywhere around us — from a simple swing in a park to the vibrations of a tuning fork.

I’m writing about this chapter because oscillatory motion is one of those topics that look simple on the surface but has deep connections across many areas of physics. Whether it’s alternating current in electricity, sound in acoustics, or waves in quantum mechanics — the concept of oscillation is everywhere. Personally, when I first learned this chapter, I was surprised how many daily life examples are based on oscillations. So if you understand this chapter well, it will help not only in school exams but also in competitive exams and even in your future physics studies. That’s why it’s important to have a reliable source like the NCERT PDF to revise from.

NCERT Class 11 Physics Chapter 13: Oscillations – Chapter Summary

This chapter introduces the basic concepts of periodic motion and develops the mathematics behind simple harmonic motion (SHM).

Key Concepts Covered

1. Periodic and Oscillatory Motion

Periodic motion repeats after equal intervals of time
Oscillatory motion is a type of periodic motion, like a pendulum

2. Simple Harmonic Motion (SHM)

Defined as motion where restoring force is proportional to displacement and directed towards mean position
Equation: F=−kxF = -kxF=−kx

3. Terms You Should Know

Amplitude (A): Maximum displacement from mean position
Time period (T): Time taken to complete one cycle
Frequency (f): Number of oscillations per second
Phase: Describes position and direction of motion

4. Mathematical Representation of SHM

Displacement: x(t)=Asin⁡(ωt+ϕ)x(t) = A \sin(\omega t + \phi)x(t)=Asin(ωt+ϕ)
Velocity: v(t)=Aωcos⁡(ωt+ϕ)v(t) = A\omega \cos(\omega t + \phi)v(t)=Aωcos(ωt+ϕ)
Acceleration: a(t)=−ω2x(t)a(t) = -\omega^2 x(t)a(t)=−ω2x(t)

5. Energy in SHM

Kinetic and potential energies change continuously
Total energy remains constant
E=12kA2E = \frac{1}{2} kA^2E=21kA2

6. Spring-Mass System and Pendulum

Time period of spring-mass: T=2πmkT = 2\pi \sqrt{\frac{m}{k}}T=2πkm
Time period of simple pendulum: T=2πlgT = 2\pi \sqrt{\frac{l}{g}}T=2πgl

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Click here to download NCERT Class 11 Physics Chapter 13: Oscillations PDF

Download NCERT Class 11 Biology Chapter 17 Hindi PDF: गमन एवं संचलन

Movement and locomotion are two of the most exciting topics students learn in Class 11 Biology, especially in the Hindi medium. Chapter 17, गमन एवं संचलन, explains how living organisms move, how muscles function, how bones support the body, and how different systems work together to enable movement. This chapter builds a strong foundation for higher studies in biology, medicine, physiotherapy and sports science.

I am writing about this chapter because I know many students struggle to find the correct NCERT PDF in Hindi, especially when preparing for exams. Having a reliable, easy-to-download PDF helps students revise whenever needed. Chapter 17 is also important because it clears concepts that often appear in competitive exams like NEET, state-level entrance tests and school-level assessments. When students understand the basics such as types of joints, structure of muscles, skeletal system and movement disorders, it becomes much easier to answer application-based and diagram-related questions. In short, having quick access to this chapter in PDF format can really boost revision speed and help students stay confident before exams.

About NCERT Class 11 Biology Chapter 17: गमन एवं संचलन

NCERT’s Chapter 17 in the Hindi Biology textbook covers the complete mechanism of movement in humans and other organisms. It explains how our bones, muscles and joints coordinate to create motion.

The chapter mainly includes:

Types of movements
Skeletal system
Types of bones and joints
Structure of muscles
Muscle contraction process
Disorders related to movement

This chapter becomes very useful later when students study human physiology in Class 12 or prepare for entrance exams.

Key Topics Covered in Chapter 17

Here are the major concepts included in गमन एवं संचलन:

Locomotion and movement – Difference between the two, with real-life examples
Skeletal system – Axial skeleton, appendicular skeleton, functions of bones
Joints – Ball and socket, hinge joints, pivot joints, gliding joints
Muscle types – Skeletal, smooth, cardiac
Muscle structure – Sarcomere, actin, myosin
Mechanism of muscle contraction – Sliding filament theory
Disorders – Arthritis, osteoporosis, myasthenia gravis

Students often find diagrams related to muscle structure and types of joints very important for exams. So, having the PDF makes it easier to refer to the diagrams anytime.