1st Year Physics Chapter 11 Notes (New Book 2025-26): Special Theory of Relativity – All Punjab Boards
What would a clock or a measuring rod show if it moved past you at nearly the speed of light? Questions like that sit at the heart of Special Theory of Relativity, Chapter 11 of the new Class 11 Physics book. The textbook was prepared under PECTAA and has been taught in Punjab since the 2025-26 session.
Relativity challenges everyday intuition, and that is exactly why it needs practice. Many students can repeat a statement from the book yet find it hard to explain in their own words or to use in a calculation. Working through varied questions helps the ideas settle until they feel less strange.
These 1st year physics chapter 11 notes help you prepare with five parts: multiple-choice questions, short and long questions with answers, solved numericals, and worked solutions to the textbook exercise. You can download them free from this page.
Punjab’s earlier Class 11 Physics book followed a different chapter plan, so notes made for it are unlikely to line up with this chapter. Choose material that is clearly made for the 2025-26 book.
The notes are intended for students under all nine Punjab boards, whether they sit their papers in Lahore, Multan, Bahawalpur or anywhere else in the province. The sections below describe the five parts, connect them to question types in the paper, and suggest a study plan for this chapter.
About Chapter 11 in brief
The title refers to special relativity, the theory Albert Einstein published in 1905, which describes motion at very high speeds. In general terms, it shows that measurements of time and length can depend on the motion of the observer, while the speed of light in a vacuum stays the same for everyone. This page describes the notes for the chapter rather than teaching the theory itself.
What’s inside the 1st year physics chapter 11 notes
The Chapter 11 file is arranged in five parts. Each targets a particular way of being tested, and together they let you move from recognising ideas to applying them.
MCQs
This part consists of multiple-choice questions on relativity. In a conceptual chapter, MCQs are useful because working out why the wrong options are wrong deepens your grasp of the right idea.
Answer a set without help, then go back over each option, not only the one you chose. Asking why each wrong option fails is one of the quickest ways to clear up confusion in this topic.
Short questions with answers
This part is a set of short questions with answers. On this chapter, they may ask you to state a basic idea of the theory, explain a term in plain language, or give a short reason for a result that seems surprising.
Read the answers for clarity rather than length. Then try answering similar questions yourself in simple English, as if explaining to a younger student. If you cannot put an idea simply, return to the textbook.
Long questions with answers
This part has long questions with detailed answers. Extended questions on special relativity may ask you to explain a principle, discuss its consequences, or describe a situation that illustrates it.
Plan before you write. Read the question, jot down three or four points in the order you will use them, and only then begin. Comparing your plan with the answer in the notes shows whether your structure is sound.
Numericals
Solved numerical problems make up this part. Calculations in relativity often involve the speed of light and speeds written as fractions of it, along with very large or very small values.
Write numbers in scientific notation from the start, and keep track of powers of ten as you go. After solving, check the solution and ask whether your result fits the idea behind the formula, for instance whether a quantity that should change only slightly really did.
Solved exercise
In this part you will find solutions to the textbook’s end-of-chapter exercise. Since the exercise is written to match the chapter, it gives you a dependable picture of what the book expects you to be able to do.
Do the exercise in rough before looking at these solutions. For conceptual questions, compare your explanation with the solution and note any idea you left out.
Why these notes are useful
Relativity can feel unfamiliar at first, so having this chapter’s practice material organised in one file is especially handy.
- Tied to the current book. The notes follow Chapter 11 of the new PECTAA textbook used from 2025-26.
- Concepts and calculations together. Written answers and solved numericals sit in one file.
- Material to test your own reasoning. Worked solutions give you something to compare your answers with.
- Free on this page. There is no fee for the download.
Relativity takes time to absorb. Treat the notes as practice support, and keep the textbook and your teacher’s explanations at the centre of your study.
Which exam questions these notes help with
The table pairs each part of the file with the type of paper question it can help you prepare for. The precise structure of the intermediate Physics paper, including choices and marks, is set by your board, so check the official pairing scheme for your session.
| Part of the notes | Matching question type |
| MCQs | Multiple-choice items in the objective part |
| Short questions with answers | Brief answers in the subjective part |
| Long questions with answers | Explanatory long answers |
| Numericals | Problems involving calculation |
| Solved exercise | Questions related to the textbook exercise |
Guess papers may claim to know which relativity questions will be set, but no such prediction is official. Prepare the chapter properly and follow your board’s official scheme instead.
How to study with these notes
Relativity is easier to learn in small, repeated steps than in one long session. A suggested approach:
- Read the chapter slowly, twice. On the first pass aim for the general idea; on the second, focus on definitions and statements.
- Write each key statement in your own words. Keep these in a short list you can revise quickly.
- Picture the situations. For each example in the book, imagine or sketch the observers and what each one measures.
- Try the textbook exercise and compare with the solved exercise. Mark any question where your idea differed from the solution.
- Practise the numericals carefully. Note down the given data, write speeds as a fraction of the speed of light where that helps, choose the formula, and keep powers of ten organised. Write the final unit and check that the size of the answer makes sense.
- Revise from the short and long answers. Rewrite a few without looking, then compare.
- Use the MCQs as a final check. Pay extra attention to any option that tempted you.
Discussing a puzzling idea with a classmate or teacher often clears it up faster than rereading it alone.
Who should use these notes
The notes are for FSc part 1 students in Punjab, in the pre-engineering and pre-medical groups, who follow the new Physics textbook. Any other intermediate student taking Physics under a Punjab board can also use them.
Private candidates preparing from the 2025-26 book may use them as well. If there is any doubt about which textbook your session uses, your college or board can confirm it.
Download the notes
The Chapter 11 file is free to download directly from this page.
Keep these special theory of relativity notes with your list of key statements, so you can revise the concepts and the worked material side by side.
Frequently asked questions
Can I use older notes for this chapter?
It is wiser not to rely on them. Special Theory of Relativity is Chapter 11 of the new PECTAA textbook used from 2025-26, and these notes are written for that book. Notes made for the earlier syllabus follow a different chapter plan.
What are the five parts of these notes?
They are MCQs, short questions with answers, long questions with answers, numericals with solutions, and the textbook exercise solved.
Is there a charge for the Chapter 11 file?
No. It is free to download here.
How can I understand relativity better if it feels confusing?
Put each idea into simple words of your own, sketch the situation, and discuss it with someone. Working out why wrong MCQ options fail also helps.
Are these notes suitable for students of the Rawalpindi board?
Yes. All Punjab boards, Rawalpindi included, use this textbook. For the paper pattern, see your board’s official pairing scheme.