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JEE Main · subject
Physics carries 25 of the 75 questions in JEE Main and 100 of the 300 marks. This page ranks all 20 syllabus units by how often past papers draw on them, names the mistake each unit usually catches, and shows where the marks you are losing actually sit.
Quick answer
BrainStride analysis of past papers · questions per shift, ranges vary · NTA publishes no chapter weightage
Unit names follow the official JEE Main syllabus. The question ranges are ours, taken from past papers; the mistake column is the slip our teachers see most often on that unit.
| Unit | Class | Questions per paper | Difficulty | The mistake it catches |
|---|---|---|---|---|
| Units and Measurements | 11 | 0–2 Q | Easy | Adding errors instead of adding relative errors when a formula multiplies quantities. |
| Kinematics | 11 | 1–2 Q | Easy–moderate | Choosing a positive direction and then abandoning it halfway through the solution. |
| Laws of Motion | 11 | 0–2 Q | Moderate | Using μmg on an incline instead of μmg cos θ. |
| Work, Energy and Power | 11 | 0–2 Q | Moderate | Applying energy conservation across a collision where energy is not conserved. |
| Rotational Motion | 11 | 1–3 Q | Moderate–hard | Recalling a moment of inertia for the wrong axis instead of using the parallel-axis theorem. |
| Gravitation | 11 | 0–2 Q | Moderate | Mixing up orbital and escape speed, which differ by a factor of √2. |
| Properties of Solids and Liquids | 11 | 1–2 Q | Moderate | Treating surface tension and viscosity formulas as interchangeable in Bernoulli problems. |
| Thermodynamics | 11 | 0–2 Q | Moderate | Sign of work done: taken as positive on the gas and by the gas in the same solution. |
| Kinetic Theory of Gases | 11 | 0–1 Q | Easy–moderate | Using the wrong degrees of freedom for a diatomic gas at high temperature. |
| Oscillations and Waves | 11 | 1–2 Q | Moderate | Confusing the amplitude and phase conventions when two SHMs are superposed. |
| Electrostatics | 12 | 2–3 Q | Moderate–hard | Treating potential as a vector, or ignoring the sign of a charge when summing potentials. |
| Current Electricity | 12 | 1–3 Q | Moderate | Redrawing a symmetric network wrongly, then solving the wrong circuit correctly. |
| Magnetic Effects of Current and Magnetism | 12 | 1–2 Q | Moderate | Direction errors: the right-hand rule applied to the current instead of the field. |
| Electromagnetic Induction and Alternating Currents | 12 | 1–2 Q | Moderate | Dropping the minus sign in Lenz’s law and getting the induced current backwards. |
| Electromagnetic Waves | 12 | 0–1 Q | Easy | Getting the spectrum order wrong when asked to compare frequency and wavelength. |
| Optics | 12 | 1–2 Q | Moderate | Sign convention in mirror and lens formulas, especially for virtual images. |
| Dual Nature of Matter and Radiation | 12 | 0–2 Q | Easy–moderate | Using energy in joules where the formula expects electron-volts. |
| Atoms and Nuclei | 12 | 1–2 Q | Easy–moderate | Binding energy per nucleon confused with total binding energy. |
| Electronic Devices | 12 | 0–2 Q | Easy | Reading a logic-gate combination without simplifying it first. |
| Experimental Skills | 11–12 | 0–2 Q | Easy–moderate | Least-count and vernier questions answered from memory rather than from the reading given. |
Ranges are per shift and overlap — a single paper has 25 Physics questions, so no shift draws on every unit.
The five our teachers correct most often — and none of them is a gap in what you know.
Why it happens
On an incline the normal force is mg cos θ, not mg, but the formula is recalled flat from memory.The fix
Draw the free-body diagram before writing a single equation, and label the normal force every time.Why it happens
A positive direction is chosen at the start and quietly abandoned when the motion reverses.The fix
Write the sign convention at the top of the rough work and check the final sign against it.Why it happens
The standard result is for an axis through the centre; the question asks about a different axis.The fix
Name the axis first, then decide whether the parallel-axis theorem applies.Why it happens
Centimetres, grams and kilovolts enter a formula that expects SI units, so correct physics scores zero.The fix
Convert every quantity to SI in the first line of the solution, before any algebra.Why it happens
Accuracy drops sharply at the end of the paper, and negative marking makes those attempts expensive.The fix
Decide in advance the last time at which you will start a new question, and revise instead after it.The 20 units grouped the way students study them. Ranges are the sum of the unit ranges above; shares use the midpoints, so they add to 100% while the ranges overlap.
| Branch | Units | Questions per paper | Share of the section | Marks at stake |
|---|---|---|---|---|
| Mechanics | 7 | 3–15 | 35% | 12–60 |
| Heat and thermodynamics | 2 | 0–3 | 6% | 0–12 |
| Oscillations and waves | 1 | 1–2 | 6% | 4–8 |
| Electricity and magnetism | 4 | 5–10 | 29% | 20–40 |
| Optics and electromagnetic waves | 2 | 1–3 | 8% | 4–12 |
| Modern physics and electronics | 3 | 1–6 | 13% | 4–24 |
| Experimental skills | 1 | 0–2 | 4% | 0–8 |
BrainStride analysis of past papers · questions per shift, ranges vary · NTA publishes no chapter weightage
Mechanics — Units and Measurements, Kinematics, Laws of Motion, Work, Energy and Power, Rotational Motion, Gravitation, Properties of Solids and Liquids — brings about 3–15 of the 25 Physics questions a shift in our reading of past papers, roughly 35% of the section, or 12–60 marks. The heaviest units inside it are Rotational Motion (1–3) and Kinematics (1–2).
Heat and thermodynamics — Thermodynamics, Kinetic Theory of Gases — brings about 0–3 of the 25 Physics questions a shift in our reading of past papers, roughly 6% of the section, or 0–12 marks. The heaviest units inside it are Thermodynamics (0–2) and Kinetic Theory of Gases (0–1).
Oscillations and waves brings about 1–2 of the 25 Physics questions a shift in our reading of past papers, roughly 6% of the section, or 4–8 marks.
Electricity and magnetism — Electrostatics, Current Electricity, Magnetic Effects of Current and Magnetism, Electromagnetic Induction and Alternating Currents — brings about 5–10 of the 25 Physics questions a shift in our reading of past papers, roughly 29% of the section, or 20–40 marks. The heaviest units inside it are Electrostatics (2–3) and Current Electricity (1–3).
Optics and electromagnetic waves — Electromagnetic Waves, Optics — brings about 1–3 of the 25 Physics questions a shift in our reading of past papers, roughly 8% of the section, or 4–12 marks. The heaviest units inside it are Optics (1–2) and Electromagnetic Waves (0–1).
Modern physics and electronics — Dual Nature of Matter and Radiation, Atoms and Nuclei, Electronic Devices — brings about 1–6 of the 25 Physics questions a shift in our reading of past papers, roughly 13% of the section, or 4–24 marks. The heaviest units inside it are Atoms and Nuclei (1–2) and Dual Nature of Matter and Radiation (0–2).
Experimental skills brings about 0–2 of the 25 Physics questions a shift in our reading of past papers, roughly 4% of the section, or 0–8 marks.
Work in the order the paper pays. Electrostatics, Current Electricity, Rotational Motion, Optics and Modern Physics together account for roughly a third of the Physics questions in our reading of past papers, and they are all chapters where a clean method beats memory. Finish those to the point where you can solve previous-year questions under time, then widen.
Two further rules hold for almost every student:
Enough to stop repeating the same error, which is a different measure from hours. In the weak-chapter map a unit is finished when your error rate on fresh questions from it falls and stays down — not when the chapter has been read. That is the standard the daily plan holds you to, and it is why two students with the same syllabus coverage get different plans.
Electromagnetic Waves, Kinetic Theory and Electronic Devices are short, largely factual and rarely carry more than one question each — which makes them cheap to finish late, not safe to skip. Leave them for the weeks when you are too tired for mechanics, and use the syllabus tracker so nothing is quietly dropped.
A Physics plan needs one problem book, not three — our best Physics books for JEE guide says which one for which stage and what to skip in each. For the weight of each unit against the other subjects, the chapter-wise weightage analysis sets Physics beside Chemistry and Maths, and the JEE Main hub keeps the pattern, syllabus and dates together. After a mock, the marks-to-percentile calculator turns the total into a percentile band, and the cutoff page shows where the JEE Advanced qualifying percentile has sat each year — the 2026 general-category line was 93.41. Mechanics and electromagnetism are also the core of JEE Advanced Physics, where the same chapters are examined with multiple-correct and numerical formats.
Formulas, the mistakes that cost marks, worked examples and a quiz — free, no account.
Everything here is free and needs no account.
Every solution is reviewed by a subject teacher before it ships, and explanations are audited weekly. The teachers are on staff, so we describe the process rather than publish a roster.
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In BrainStride’s analysis of past JEE Main papers, Electrostatics (2–3 questions), Current Electricity (1–3), Rotational Motion (1–3) and Modern Physics — Dual Nature plus Atoms and Nuclei — (2–4 together) carry the most. NTA publishes no official chapter weightage, so treat these as ranges from past papers rather than a guarantee for 2027.
Modern Physics — Dual Nature of Matter and Radiation, together with Atoms and Nuclei — accounts for about two to four of the 25 JEE Main Physics questions in our reading of recent papers. Electronic Devices adds up to two more. These chapters are short and largely formula-driven, which is why they repay revision time faster than mechanics.
Most students find JEE Main Physics harder to score in than Chemistry, because Physics questions usually need a derivation or a multi-step calculation while Chemistry rewards recall in inorganic and NCERT-line questions. Both carry 25 questions and 100 marks, so the honest answer is that Physics costs more time per mark.
No chapter is safe to skip in JEE Main Physics. A shift usually samples fifteen or more of the twenty syllabus units at one or two questions each, so dropping even a short unit like Electromagnetic Waves risks four marks and a negative mark if you guess. Finish the high-weightage units first, then close the small ones.
For a Class 12 student studying alongside school and coaching, a first pass through the twenty JEE Main Physics units usually takes four to six months, with revision and practice continuing after that. Droppers compress it into three to four months. The honest measure is not coverage but whether your error rate on fresh questions falls.
Silly errors in Physics are patterns, not accidents: unconverted units, dropped signs, and the wrong axis for a moment of inertia. BrainStride tags every wrong answer as a concept gap, a silly error or time pressure, and sends accuracy drills when the tag is a silly error, so the specific slip is practised rather than the whole chapter.
BrainStride is not affiliated with NTA. Chapter weightage is our own analysis of past papers — NTA publishes none. Confirm the syllabus and pattern against the current official bulletin.
Twenty minutes of diagnostic answers that, then writes the daily plan that closes them. Free, no card.