Radioactivity is an important topic in the JEE Advanced Physics syllabus, primarily falling under the domain of Modern Physics. It comprises the decay of atomic nuclei, the emission of particles (such as alpha, beta, and gamma radiation), and the associated concepts such as half-life, decay constant, and nuclear reactions.
In terms of weightage, the Modern Physics unit (which includes Radioactivity) is approximately 20-25% of the total marks in the JEE Advanced Physics paper. Radioactivity is generally 4-6% of the total marks, which would equate to 1 to 2 questions per year. The questions asked in the portion can, on occasion, range from basic to feasible, and some questions may utilize equations while still relying on physical concepts.
Modern Physics - JEE Advanced
Modern Physics is an important part of the Physics syllabus for JEE Advanced. This syllabus consists of physical concepts that were revolutionized in the 20th century to give a new perspective on understanding the physical world. The more important topics that fall under the umbrella of "Modern Physics" include the Photoelectric Effect, Atomic Models, Nuclear Physics, Radioactivity, Dual Nature of Matter, and Binding Energy.
In JEE Advanced, you can expect around 2-3 questions from this section. It includes conceptual clarity and problem solving in Modern Physics. Nuclear Physics (calculation of Mass Defect and Binding Energy), Quantum Mechanics, and the Photoelectric Effect are important topics to focus on as questions frequently appear from those subjects.
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JEE Advanced Previous Year Question Paper
Here are some of the most important JEE Advanced Previous Year Questions of Radioactivity.
Question 1:
The 8th bright fringe above the point O oscillates with time between two extreme positions. The separation between these two extreme positions, in micrometer (µm), is.
Question 2:
The maximum speed in µm/s at which the 8th bright fringe will move is.
Question 3:
If the collision occurs at time \( t = 0 \), the value of \( \frac{v_{cm}}{(a\omega)} \) will be:
Question 4:
If the collision occurs at time \( t = 0 \), the value of \( \frac{v_{cm}}{(a\omega)} \) will be:
Question 5:
A spherical soap bubble inside an air chamber at pressure \( P_0 = 10^5 \) Pa has a certain radius so that the excess pressure inside the bubble is \( \Delta P = 144 \) Pa. Now, the chamber pressure is reduced to \( \frac{8P_0}{27} \) so that the bubble radius and its excess pressure change. In this process, all the temperatures remain unchanged. Assume air to be an ideal gas and the excess pressure \( \Delta P \) in both the cases to be much smaller than the chamber pressure. The new excess pressure \( \Delta P \) in Pa is ___.
Question 6:
A table tennis ball has radius \( \frac{3}{2} \times 10^{-2} \, \text{m} \) and mass \( \frac{22}{7} \times 10^{-3} \, \text{kg} \). It is slowly pushed down into a swimming pool to a depth \( d = 0.7 \, \text{m} \) below the water surface and then released from rest. It emerges from the water surface at speed \( v \), without getting wet, and rises to a height \( H \). Which of the following option(s) is/are correct? [Given: \( \pi = \frac{22}{7}, g = 10 \, \text{m/s}^2, \text{density of water} = 1 \times 10^3 \, \text{kg/m}^3, \text{viscosity of water} = 1 \times 10^{-3} \, \text{Pa.s} ]
Question 7:
The dimensions of a cone are measured using a scale with a least count of 2 mm. The diameter of the base and the height are both measured to be 20.0 cm. The maximum percentage error in the determination of the volume is _______.
Question 8:
A ball is thrown from the location \((x_0, y_0) = (0, 0)\) of a horizontal playground with an initial speed \(v_0\) at an angle \(\theta_0\) from the \(+x\)-direction. The ball is to be hit by a stone, which is thrown at the same time from the location \((x_1, y_1) = (L, 0)\). The stone is thrown at an angle \((180^\circ - \theta_1)\) from the \(+x\)-direction with a suitable initial speed. For a fixed \(v_0\), when \((\theta_0, \theta_1) = (45^\circ, 45^\circ)\), the stone hits the ball after time \(T_1\), and when \((\theta_0, \theta_1) = (60^\circ, 30^\circ)\), it hits the ball after time \(T_2\). In such a case, \(\left( \frac{T_1}{T_2} \right)^2\) is ________.
Question 9:
The minimum kinetic energy needed by an alpha particle to cause the nuclear reaction
\( ^{16}_7 N + ^{4}_2 He \rightarrow ^{1}_1 H + ^{19}_8 O \) in a laboratory frame is \(n\) (in MeV). Assume that \( ^{16}_7 N \) is at rest in the laboratory frame. The masses of \( ^{16}_7 N, ^{4}_2 He, ^{1}_1 H \) and \( ^{19}_8 O \) can be taken to be 16.006u, 4.003u, 1.008u and 19.003u, respectively, where 1u = 930 MeV/c². The value of \(n\) is ________.
Question 10:
In a radioactive decay chain reaction, \( ^{230}_{90} Th \) nucleus decays into \( ^{214}_{84} Po \) nucleus. The ratio of the number of \( \alpha \) to number of \( \beta^- \) particles emitted in this process is ________.
JEE Advanced Exam Pattern
The JEE Advanced exam is considered as one of the top engineering entrance examinations in India, which takes place annually for enrollment at IITs and other top institutions to undergraduate programs. JEE Advanced consists of two compulsory papers, Paper 1 and Paper 2, each with three hours of duration. It challenges students’ knowledge of Physics, Chemistry and Mathematics. The exam consists of different question types including Multiple Choice Questions (MCQs), Numerical Value-based Questions and Assertion-Reasoning questions to evaluate the foundational knowledge of topics and ability to solve problems. Both papers have a total of 180 marks, with marks deducted for incorrect answers in a few question types.
| Aspect | Details |
|---|---|
| Mode | Computer-Based Test (CBT) |
| Papers | 2 (Paper 1 & Paper 2) – Both mandatory |
| Duration | 3 hours per paper (with break between papers) |
| Total Subjects | Physics, Chemistry, Mathematics (Equal weightage) |
| Total Questions | ~54–60 (18–20 per subject, split across question types) |
| Language | English & Hindi (option to switch during exam) |
The exam is known for its challenging nature and is conducted in English and Hindi. It is essential to clear the JEE Main exam before appearing for JEE Advanced.
Question Type & Marking Scheme
Here is a detailed marking scheme for different questions in JEE Advanced exam.
| Question Type | Marks per Q | Negative Marking | Examples |
|---|---|---|---|
| Single Correct MCQ | +3 | -1 | Basic theory/direct formula questions |
| Multiple Correct MCQ | +4 (full) | -2 (if all wrong) / Partial marks* | "Which of the following is/are true?" |
| Numerical Value (NV) | +3 | No negative | Calculations (e.g., wavelength) |
| Paragraph-Based | Varies (2–4) | Depends on sub-type | Linked to a common scenario |
| Match the Following | +2 per match | -1 per wrong match | Column matching (e.g., graphs) |
Partial Marks: For Multiple Correct MCQs, +1 per correct option (if not all selected).
Subject-Wise Distribution (Per Paper)
Here is the subject wise questions distribution in the JEE Advanced exam.
| Subject | MCQs | Numerical | Paragraph/Matching | Total |
|---|---|---|---|---|
| Physics | 6–8 | 4–5 | 2–3 | 12–16 |
| Chemistry | 6–8 | 4–5 | 2–3 | 12–16 |
| Maths | 6–8 | 4–5 | 2–3 | 12–16 |
Subject wise Syllabus: JEE Advanced 2025
Here is a quick syllabus of JEE Advanced 2025 subject wise which helps in preparation of the students. Check JEE Advanced Syllabus for a detailed Syllabus.
| Subject | Key Topics |
|---|---|
| Physics | Mechanics, Electrodynamics, Modern Physics, Optics, Thermodynamics, Error Analysis |
| Chemistry | Physical (Thermo, Kinetics), Organic (Reactions), Inorganic (Coordination, P-Block) |
| Maths | Algebra, Calculus, Coordinate Geometry, Trigonometry, Vectors |
Note:
- Physics: Focus on Modern Physics (20% weightage) & Electrodynamics.
- Chemistry: Organic reactions & Coordination compounds are high-scoring.
- Maths: Calculus (35% weightage) is most critical.
In addition to conceptual knowledge, you should practice multiple mock tests before your exam.
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JEE Advanced Physics Paper Analysis (2024 & Trends)
The JEE Advanced Physics Paper is designed to test a candidate in terms of knowledge in Physics as well as problem-solving skills and capabilities. The test consists of two papers, Paper 1 and Paper 2, with each paper being 3 hours in length and comprising an approximate number of 18-20 questions. The questions in both papers, while relating to a wide range of Physics Topics such as Mechanics, Electromagnetism, Optics, Thermodynamics, Modern Physics, Waves and Oscillations, etc., have the same syllabus in all subjects within the two papers.
Overview (2024)
Here is a basic overview of JEE Advanced Physics Pattern in 2024
| Aspect | Details |
|---|---|
| Total Questions | 12–14 per paper (2 papers) |
| Difficulty | Moderate to Hard (30% easy, 50% moderate, 20% difficult) |
| Question Types | Single/Multiple MCQs, Numerical Value, Paragraph-based, Match-the-Column |
| Key Focus Areas | Modern Physics, Electrodynamics, Mechanics, Error Analysis |
Chapter-Wise Weightage (2024)
The Physics subject in JEE Advanced incorporates a range of chapters from the Class 11 and Class 12 syllabus. The weightage from each chapter varies within each subject. Below is the subject-wise weightage of Physics subjects and possible weightage in JEE Advanced.
| Topic | Weightage | Difficulty | Remarks |
|---|---|---|---|
| Modern Physics | 20–25% | Moderate | Nuclear physics, photoelectric effect, semiconductors |
| Electrodynamics | 18–22% | Hard | EMI, Capacitors, AC circuits, Maxwell’s laws |
| Mechanics | 15–20% | Moderate-Hard | Rotational dynamics, center of mass, collisions |
| Thermodynamics & KTG | 12–15% | Moderate | Laws of thermodynamics, kinetic theory |
| Optics | 10–12% | Easy-Moderate | Wave optics, interference, diffraction |
| Error Analysis | 8–10% | Tricky | Vernier calipers, screw gauge, least count |
| Waves & SHM | 5–8% | Easy | Standing waves, Doppler effect, spring-mass systems |
Difficulty Trends (2019–2024)
Based on previous year trends, here is an overview of the JEE Advanced Question Paper based on its difficulty level and focus points of the exam.
| Year | Difficulty Level | Key Observations |
|---|---|---|
| 2024 | Moderate-Hard | More numerical-based questions, fewer theory MCQs |
| 2023 | Moderate | Balanced mix of conceptual and formula-based Qs |
| 2022 | Hard | Heavy focus on electromagnetism and modern physics |
| 2021 | Very Hard | Unconventional mechanics problems, lengthy solutions |
| 2020 | Moderate | More NCERT-aligned questions |
JEE Advanced Previous Year Question Papers with Detailed Solutions
JEE Advanced 2024 Question Paper Pdf with Solutions
| Paper Name | Question Paper Link | Solutions Link |
|---|---|---|
| JEE Advanced 2024 Paper 1 Question Paper (English) | Download PDF | Check Solutions |
| JEE Advanced 2024 Paper 2 Question Paper (English) | Download PDF | Check Solutions |
| JEE Advanced 2024 Paper 1 Question Paper (Hindi) | Download PDF | Check Solutions |
| JEE Advanced 2024 Paper 1 Question Paper (Hindi) | Download PDF | Check Solutions |
JEE Advanced Question Paper has 4 sections- Section 1 (Maximum marks-12), Section 2 (Maximum marks-12), Section 3 (Maximum marks- 24) and Section 4 (Maximum marks-12)
JEE Advanced Architecture Aptitude Test Question Paper 2024 with Solutions
| Paper Name | Question Paper Link | Solutions Link |
|---|---|---|
| Architecture Aptitude Test | Download PDF | Check Solutions |
JEE Advanced 2023 Question Paper PDF Download With Solutions
| Paper | Question Paper PDF | Answer Key PDF |
|---|---|---|
| Question Paper 1 PDF | Download PDF | Check Solutions |
| Question Paper 2 PDF | Download PDF | Check Solutions |
| Question Paper AAT PDF | Download PDF | Check Solutions |
JEE Advanced 2022 Question Paper
| 2022 Question Paper | PDF Download |
|---|---|
| Question Paper 1 PDF | Click here |
| Question Paper 2 PDF | Click here |
JEE Advanced 2021 Question Paper
| Question Paper | PDF Download | ||
|---|---|---|---|
| Question Paper 1 PDF | Physics | Chemistry | Maths |
| Question Paper 2 PDF | Physics | Chemistry | Maths |
JEE Advanced 2020 Question Paper
| Question Paper | PDF Download |
| Question Paper 1 PDF | Click here |
| Question Paper 2 PDF | Click here |
Frequently Asked Questions (FAQs)
Q1. Is radioactivity important for JEE Advanced?
Answer. Indeed, the subject of radioactivity is of value to JEE Advanced, primarily as part of the Physics domain. It is referenced within the chapter "Nuclei" which discusses topics such as radioactive decay, half-life, and decay constant. Understanding such concepts is important for understanding how a nuclear reaction works, how radioactive materials behave, and more specifically, how we calculate the decay of a radioactive substance over time. Radioactivity will typically be referenced within theoretical questions and a numerical question in the exam.
Q2. Is modern physics important for JEE Advanced?
Answer. Certainly! Modern Physics holds a significant value for JEE Advanced as it contributes about 10-15% of the total marks in Physics. This topic includes important chapters like Atomic Structure, Photoelectric Effect, Nuclear Physics, Binding Energy, etc. In any case, proving your mastery over this section is critical for performing well in this subject.
Q3. Is it easy to score 150 in JEE Advanced?
Answer. Obtaining 150 marks in the JEE Advanced can be challenging but can be achieved through discipline and a strong grasp of the concepts. The competitive nature of the exam and the depth of knowledge required to answer the exam questions test the candidate's aptitude in problem-solving, exam strategy, and effective use of time. While 150 marks is by comparison a good score, it does require breadth of knowledge across each of the three subjects: Physics, Chemistry, and Mathematics; it also requires practice of problems; and most importantly it requires a calm composure in the exam itself. The greatest contributing factor to success in the exam is the quality of preparation, and then, ongoing focus and practice.
Q4. Is radioactivity a tough chapter?
Answer. Radioactivity can be seen as a somewhat challenging chapter in the subject of JEE Advanced. This chapter covers understanding concepts such as decay laws, half-life, decay constant, and nuclear reactions, which involve some understanding of concepts and mathematics. Questions usually require numerical working out and conceptual understanding, which some students may find challenging. It can be made easier through the application of practice, a clear understanding of theory, and regular problem solving.
Q5. What is the weightage of radioactivity in JEE Advanced?
Answer. The radioactivity chapter in JEE Advanced weighs about 2-3% of the total marks in the Physics section. Though it is not a large portion of the subject, it is still an important topic within the chapter of "Nuclei" and can give you a few direct or indirect questions on this topic. The radioactivity chapter is really small, and most of the concepts are important. So it's worthwhile devoting study to it, but it should not come at the expense of other big areas in Physical Science.
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