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Welcome to Special Theory of Relativity

In our daily life,  we observe many relative facts like when we travel through by a superfast train we see plants, building near to the railway track are moving in the opposite direction. The speed of plants seems slow or fast in the opposite direction at the speed of the train. In the same way, we observe it when we travel by car. The car coming towards me seems moving so fast compared to the car which is moving parallel to me in the same direction. While the one who is standing on the surface observe the same speed for both the cars and train in the above example.

Why it so happen for one event which I see at my place is not the same for another one at his place? You may also hear about the twin paradox concept. In this example, there are two twin one of them at the age of 20 yrs start his journey for a particular planet in space and move with speed of light relative to the earth. When he comes back to the earth after completing one year he observed older to his twin brother, how and why?

What are time dilation and length contraction? How we can add relative velocities and define relativistic mass and relativistic energy? There are so many questions and their answers with the concept and numerical.

In this physics course, I have provided the basic and fundamental concepts of the special theory of relativity. As you know, to understand the topics of physics we also need some other physical concepts too. I called them Supporting Physical Concepts (SPCs), these concepts are the key controller to understand any difficult problem, or topic. So the learner gets familiar about any topic or that importance, it not only creates the interest but also involves the students in the creation of innovations.

This course is a part of “Classical Mechanics and Theory of Relativity” of B. Sc. (Physics) Hons. and regular Ist year course of various universities, like

Kurukshetra University, Kurukshetra; Panjab University, Chandigarh; University of Calcutta, Kolkata; Magadh University; Utkal University; University of Calicut; University of Lucknow; University of Delhi and many others associated colleges.

For the course, I am upgrading the interacting videos by which you can submit your quizzes through videos and can submit at last after watching it fully. In addition to this quizzes are prepared for testing the learning in steps.

Galilean Transformation

Main Features

Every chapter includes quizzes based on true/false, single choice and/or multiple-choice questions, so a reader can check the learning. In some cases, PDF copy also provided so it can help you to revise the topics. Not only quizzes but related experiments/simulations are also planned to incorporated soon.

  • Quiz
  • Notes
  • Experiments  

Why This Course?

  1. This course will be helpful to Graduate and postgraduate student for basic concepts.
  2. Cover all major topics for all Universities/Institutes syllabus
  3. Basic fundamentals along with the latest developments
  4. The practice of understanding the course content in brief with Numerical Problems.
  5. A solution of the Sample question paper.
  6. Demonstration of the related experiments or simulations and related viva questions.

Course Fee:

It is free, no registration fee required.

For doubt and any other problems

Weekly online interaction is possible for any doubt and problem.

Sample Quiz

1. Heisenberg uncertainty relation holds good for


2. The energy of a particle in an infinite potential well is


3. Which of the following relation is not true according to uncertainties principle


4. The momentum of a photon is given by relation


5. The equation of motion of matter wave is given by


6. The de Broglie wavelength of a material particle depends on




User Avatar Dr Sushil Kumar

Dr. Sushil Kumar, a physicist, an eminent researcher and a teacher for the benefit of students and fellow physicists alike. Apni Physics is an effort to create a better platform and also to help the students to be able to have content at their hands whenever they want, online. Dr. Sushil continues to upload his lectures and post articles about latest researches in physics, academic, physics education, and also lessons about daily life and how physics define every aspect of our everyday movement and life.


  1. Nitish

    Sir electrodynamic ka topic kon se syllabus me hai ,please help me sir

    1. Dr Sushil Kumar

      Engineering Physics course…or you can search

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