Strategy
Score 70+ in PART B Physics with ~50 hours
25 PART B Physics questions × 4 marks − 1.33 per wrong. Three skill strands with a %HARD-aware drill posture per chapter.
- marks out of 100
- 70+
- attempts of 25
- 20
- accuracy needed
- 90%
- total prep time
- ~50 h
The arithmetic of 70+
PART B Physics has ~25 questions on the GAT (sometimes 20–28), each worth 4 marks with −1.33 per wrong. To net 70+ marks:
| Accuracy | Attempts | Correct | Wrong | Net marks | Result |
|---|---|---|---|---|---|
| 75% | 20 | 15 | 5 | ~53 | Miss |
| 90% | 20 | 18 | 2 | ~69 | Close ✓ |
| 95% | 22 | 21 | 1 | ~83 | Target ✓ |
Target: attempt 20 questions at 90%+ accuracy. Skip the 5 you’re unsure of. The −1.33 penalty per wrong is harsher than NDA Maths’ −0.83 — skipping is strictly correct when you’re below ~55% confident.
Recall — Sound · Modern Physics · Astronomy · Energy · Units (79 q · 18% of bank)
Pure fact recall — definitions, names, units, instrument identification, scientist–discovery pairs, EM spectrum order. 79 q at an average of 2% HARD. The single highest marks-per-hour strand in the bank. Don't be too cool to drill these — Modern Physics has 0 HARD across 10 years, Astronomy has 0 HARD across 4 q.
The approach
- Read /guide/nda-physics/formulas once for the formula list, but the Recall strand needs almost none of them. The work here is flashcards + statement-truth practice.
- Sound is bigger than you think (34 q). Drill all 4 subtopics: foundations (what sound is, pitch/loudness/quality, the ear), the wave equation v=fλ + speed + frequency bands, sound behaviours (echo, reverberation, beats), and applications (SONAR, transducers, instruments).
- Modern Physics is tiny (25 q) but rewards memorisation discipline: 12 scientist–discovery pairs across 10 years (Chadwick=neutron, Einstein=photoelectric, Marie Curie=radium); the 5 acronym expansions (LED, LASER, NMR, MRI, MASER); the 3-tier atomic-model history.
Sound
34 questions · 3% hard
34 q / 1 HARD in 10 yrs. Every subtopic at ≤15% HARD. Drill all four subtopics — there's no skip-list.
Modern Physics
25 questions · 0% hard
25 q · 0 HARD across the bank. Pure memorisation. Read end-to-end once, flashcard the scientist pairs + acronyms, done.
Units, Measurement and Dimensions
14 questions · 7% hard
14 q · 1 HARD across 10 yrs. SI vs CGS recall (1 dyne = 10⁻⁵ N, 1 erg = 10⁻⁷ J), the 6 most-tested dimensional formulas (G, h, force, pressure, energy, viscosity), 'which is dimensionless?'.
Drill
- Units and DimensionsDrill
Astronomy and Space
4 questions · 0% hard
4 q in 10 yrs. Memorise: 1 light year ≈ 9.46×10¹⁵ m, 1 parsec ≈ 206265 AU, Jupiter largest planet, black hole = collapsed star remnant. Done in 15 minutes.
Drill
- Astronomy and SpaceDrill
Energy Sources
2 questions · 0% hard
2 q in 10 yrs. Conventional (coal/oil/gas) vs non-conventional (solar/wind/tidal/geothermal); bio-mass = wood/dung/agri-waste (not coal). Read once.
Drill
- Energy SourcesDrill
Apply — Light · Laws of Motion · Kinematics · WEP · Gravitation · Oscillations (215 q · 48%)
The formula-engine strand. Almost half the bank. Each chapter is anchored on 1–3 named formulas (mirror formula, lens formula, Snell's law, F=ma, p=mv, KE=½mv², F=Gm₁m₂/r², T=2π√(L/g)). The work is recognising which formula a question wants, plugging in the numbers, watching the sign convention. %HARD varies 9–25% across chapters but the lever is the same: know the formula, watch the units, do the algebra.
The approach
- Memorise /guide/nda-physics/formulas. Half this strand is direct plug-in; the other half is symbol recall (which f is focal length, which v is velocity vs voltage).
- Light and Optics is the largest chapter in the bank (97 q). Drill subtopic-by-subtopic, not all at once — Light Phenomena (29 q) is recall, Reflection (18 q) is mirror formula, Refraction (17 q) is Snell + TIR, Lenses (12 q) is lens formula + power, Prisms (8 q) is dispersion + minimum deviation.
- Kinematics is small (24 q) but 25% HARD. The HARD pool concentrates in Vectors and Position (3 q at 67% HARD) and Equations of Motion graphs. Drill V-T / X-T graph reading separately — it's a distinct skill from kinematic-equation plug-in.
Light and Optics
97 questions · 10% hard
Largest chapter (97 q). Half recall (Light Phenomena, Eye + Instruments — 42 q), half formula-apply (Reflection, Refraction, Lenses, Prisms — 55 q). Target the Lenses subtopic HARD pool (25% HARD) with sign-convention practice.
Drill
HARD-target
These subtopics carry the chapter’s HARD pool — extra reps with a HARD-only drill filter pay off.
- Reflection and MirrorsDrill HARD
- Lenses and Lens FormulaDrill HARD
Laws of Motion and Forces
41 questions · 10% hard
41 q · 10% HARD. Grew dramatically 2023–24 (3→10 q/year). Newton's three laws statement-truth dominates; collision + recoil-momentum is the second pillar. Drill all five subtopics.
Kinematics and Motion
24 questions · 25% hard
24 q · 25% HARD. Small chapter, dense HARD load. Vectors and Position (3 q at 67% HARD) is a calculus-leaning topic — skip if rushed. Drill Equations of Motion (15 q) carefully — graph-reading is a distinct sub-skill.
Skip
- Vectors and Position
Work, Energy and Power
23 questions · 9% hard
23 q · 9% HARD. KE↔PE conversions dominate. F·d cosθ definition (the 'no work done when perpendicular' trap). Simple Machines is the lever-class identification recall corner.
Gravitation
17 questions · 12% hard
17 q · 12% HARD. The 'planet-scaled' ratio shape recurs — given a new planet's R and ρ relative to Earth, compute g / escape velocity / orbital period. Kepler's third law T²∝R³ is the second pillar.
Oscillations and Waves
13 questions · 15% hard
13 q · 15% HARD. The Simple Pendulum T=2π√(L/g) ratio-question is the recurring shape: change L by k, change g by m, find new T. Mass is irrelevant — that's the test.
Reason — Electricity & Magnetism · Heat · Fluid Mechanics (155 q · 35%)
The HARD-concentrated strand. 3 chapters, 35% of the bank, 22% average HARD share — and the dominant HARD subtopics here (Resistance & Circuits 42%, Calorimetry 31%, Thermo Processes 33%, Buoyancy 31%, Pressure 29%) are where the candidates who 'know the formula' still fail. The lever is multi-step computational reasoning: heat balance with phase change, series-vs-parallel resistor combinatorics, density-mixing with ratio inversion.
The approach
- Don't read these chapters end-to-end. Pick the HARD subtopic, work 10 timed PYQs on it, then move on. The HARD pool is too dense to digest in one sitting.
- Combination of Resistors is the bank's #1 marks-per-hour HARD pool (16 q at 38% HARD). Train the 5-shape repertoire: pure series, pure parallel, mixed series+parallel, ladder/infinite networks, and the 'wire of resistance R cut into pieces' shape.
- Calorimetry traps share a fingerprint — mass × specific heat × ΔT for both sides PLUS the latent heat term for any phase boundary crossing. Skip a latent term once and the whole equation is off. Practice the 'ice + water at different temperatures' question 10 times.
- Buoyancy ratio puzzles (densities mixed by equal-volume vs equal-mass) and the 'sealed packet in liquid' shape are template-driven — once you've worked 5, you've seen 80% of the test forms.
Electricity and Magnetism
93 questions · 22% hard
93 q · 22% HARD — the bank's biggest chapter for HARD. Combination of Resistors (16 q at 38% HARD) is the priority. Drill all nine subtopics; HARD-target Combination of Resistors and Power/Energy/Heating for extra reps.
Drill
HARD-target
These subtopics carry the chapter’s HARD pool — extra reps with a HARD-only drill filter pay off.
- Combination of ResistorsDrill HARD
- Electrical Power, Energy and HeatingDrill HARD
Heat and Thermodynamics
39 questions · 21% hard
39 q · 21% HARD. Calorimetry mixing (13 q at 31% HARD) + Thermo Processes (6 q at 33% HARD) are the HARD pool. Temperature scales + Phase Change are the EASY plumbing.
Drill
HARD-target
These subtopics carry the chapter’s HARD pool — extra reps with a HARD-only drill filter pay off.
- Heat, Calorimetry and Specific HeatDrill HARD
- Thermodynamic ProcessesDrill HARD
Fluid Mechanics and Properties of Matter
23 questions · 30% hard
23 q · 30% HARD — the chapter with the highest %HARD in the bank. Both subtopics > 28% HARD. Drill ratio-trap templates: density mixing by equal volume vs equal mass, sealed packet pushed under in lighter/denser liquid.
HARD-target
These subtopics carry the chapter’s HARD pool — extra reps with a HARD-only drill filter pay off.
- Buoyancy, Density and FlotationDrill HARD
- Pressure and Surface TensionDrill HARD
Test-day attempt order — for PART B Physics’s 30-minute slot
Bank Recall marks first (fast, high-confidence), then Apply, then Reason. Within the GAT 2-hour total, PART B Physics is ~30 min — this plan fits inside it.
- 8min
Sweep Recall (Sound + Modern + Astronomy + Units)
Scan all 25 Physics questions, mark every Sound/Modern Physics/Astronomy/Units/Energy Sources item, attack them first. Expect 6–8 Recall items per paper at ~30 sec each. Target: 6 correct in 8 min. If you don't know an item cold, skip — the −1.33 penalty for wrong answers makes a guess negative-EV at 50% confidence.
- 14min
Sweep Apply (Light + Laws + Kinematics + WEP + Gravity + SHM)
Attempt every direct-formula question. Light & Optics dominates here (~5 q per paper), then Laws of Motion (2 q), the rest scattered. ~12 items × ~70 sec/q. Target: 9–10 correct. If a question needs a formula you don't recall, skip — Apply strand is where overconfident plug-in mistakes happen.
- 8min
Reason last (Circuits + Calorimetry + Buoyancy)
Tackle the HARD pool last. ~5 items × ~100 sec/q. If a circuit diagram looks like an 'infinite resistor network' or a calorimetry problem has 3 phase-changes, skip — those swallow 5+ minutes each. Take only the 2–3 questions you can confidently set up the equation for. Banking 12 attempts at 90% accuracy beats 20 attempts at 60%.
Skip is not failure on the Reason strand. A 5-min calorimetry problem you can’t set up burns the budget for 4 confident Recall items. Banking 18 confident attempts beats 25 mixed-confidence attempts.
Time investment plan
| Strand | Hours | Outcome |
|---|---|---|
| Recall — Sound + Modern + Astronomy + Units | 8 | ~7 marks/paper |
| Apply — Light + Laws + Kinematics + WEP + Gravity + SHM | 22 | ~18 marks/paper |
| Reason — Circuits + Calorimetry + Fluid | 14 | ~9 marks/paper |
| Past papers, timed (last 3 years) | 6 | Calibration + speed |
| Total | 50 | Target: 70+ marks |
That’s about 7 weeks at 7 hours/week. The Apply strand takes the most hours because it spans 6 chapters; Reason has only 3 chapters but the highest hours-per-chapter ratio because the HARD pool demands timed practice.
Start with the Recall strand — guaranteed marks
79 questions across 5 chapters at 2% average HARD. Highest marks-per-hour in the bank — bank these before touching anything calculation-heavy.