In short: ICSE Class 10 Physics (Science Paper 1) has 9 major chapters with roughly 80+ formulas you need to know for the 2027 board exam. This post lists every formula chapter-wise — Force, Work Energy & Power, Machines, Refraction of Light, Sound, Current Electricity, Electrical Power & Household Circuits, Calorimetry, and Radioactivity. Each table includes the formula, the quantity it calculates, its SI unit, and exam-relevant notes. Based on the Selina Concise Physics textbook and the latest CISCE syllabus. Bookmark this page and revise one chapter a day.
Why a Formula Sheet Matters for ICSE Physics
The ICSE Physics paper is 80 marks — 40 marks from Section A (compulsory short answers) and 40 marks from Section B (choose 4 out of 6 long-answer questions). Numericals make up roughly 35–40% of the total paper. Without formulas at your fingertips, you cannot attempt these.
The ICSE Class 10 Science chapter-wise marks weightage shows that Current Electricity, Light, and Machines are the heaviest-scoring chapters. Having every formula memorized for these chapters alone can secure 25+ marks.
Here is the complete list, organized exactly as your Selina Concise Physics chapters go.
Chapter 1: Force
| Formula | Quantity | SI Unit | Notes |
|---|---|---|---|
| F = ma | Force | Newton (N) | Newton's 2nd law. 1 N = 1 kg·m/s² |
| W = mg | Weight | Newton (N) | g = 9.8 m/s² (use 10 m/s² if specified) |
| p = mv | Momentum | kg·m/s | Vector quantity — has direction |
| Impulse = F × t | Impulse | N·s | Impulse = Change in momentum (F·t = Δp) |
| F = Δp / Δt | Force (momentum form) | Newton (N) | Rate of change of momentum |
| F₁t₁ = F₂t₂ | Conservation of impulse | — | Same change in momentum, different force-time |
| m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂ | Conservation of momentum | kg·m/s | Total momentum before = after (no external force) |
| Moment = F × d | Moment of force | N·m | d = perpendicular distance from pivot |
| Clockwise moment = Anticlockwise moment | Principle of moments | — | Condition for equilibrium |
| g = GM/R² | Acceleration due to gravity | m/s² | G = 6.67 × 10⁻¹¹ N·m²/kg² |
Exam tip: ICSE loves numerical problems on conservation of momentum. Always define direction (positive/negative) before substituting values — mixing signs is the #1 error in this chapter.
Chapter 2: Work, Energy and Power
| Formula | Quantity | SI Unit | Notes |
|---|---|---|---|
| W = F × s × cos θ | Work done | Joule (J) | θ = angle between force and displacement |
| W = F × s | Work done (simplified) | Joule (J) | When force and displacement are in same direction (θ = 0°) |
| KE = ½mv² | Kinetic energy | Joule (J) | Energy due to motion |
| PE = mgh | Gravitational potential energy | Joule (J) | h = height above reference point |
| TE = KE + PE | Total mechanical energy | Joule (J) | Remains constant in absence of friction |
| P = W / t | Power | Watt (W) | 1 W = 1 J/s |
| P = F × v | Power (velocity form) | Watt (W) | When force and velocity are in same direction |
| η = (Useful work output / Total work input) × 100 | Efficiency | % | Always less than 100% in practice |
| 1 kWh = 3.6 × 10⁶ J | Energy conversion | — | 1 kilowatt-hour = 1000 W × 3600 s |
Key point tested every year: At the highest point of a freely falling body, KE = 0 and PE = max. At the lowest point, KE = max and PE = 0. Total energy remains constant throughout. Draw the energy vs height graph for 2-mark questions.
Chapter 3: Machines
| Formula | Quantity | SI Unit | Notes |
|---|---|---|---|
| MA = Load / Effort | Mechanical advantage | No unit (ratio) | MA > 1 means force is multiplied |
| VR = Distance moved by effort / Distance moved by load | Velocity ratio | No unit (ratio) | Depends only on geometry, not on friction |
| η = (MA / VR) × 100 | Efficiency | % | For ideal machine, η = 100% (MA = VR) |
| MA = η × VR / 100 | MA from efficiency | — | Useful when efficiency is given |
Lever Formulas
| Formula | Quantity | Notes |
|---|---|---|
| Load × Load arm = Effort × Effort arm | Principle of lever | Condition for equilibrium |
| MA = Effort arm / Load arm | MA of lever | Also equals Load/Effort |
| VR = Effort arm / Load arm | VR of lever | Same as MA for ideal lever |
Pulley Formulas
| Formula | Quantity | Notes |
|---|---|---|
| Single fixed pulley: VR = 1 | VR | Only changes direction, no force gain |
| Single movable pulley: VR = 2 | VR | Ideal MA = 2 |
| Block and tackle: VR = n | VR | n = number of pulleys in movable block (or total segments supporting load) |
Inclined Plane Formulas
| Formula | Quantity | Notes |
|---|---|---|
| VR = l / h | VR of inclined plane | l = length of plane, h = height |
| MA = sin θ (ideal) | MA when no friction | θ = angle of inclination |
| Effort (ideal) = mg sin θ | Effort along the plane | Component of weight along the plane |
| Effort (with friction) = mg sin θ + f | Effort with friction | f = frictional force |
Common numerical trap: Students confuse "effort arm" with "load arm" for Class 2 levers. Remember — in a Class 2 lever (like a nutcracker or wheelbarrow), the load is between the fulcrum and the effort, so the effort arm is always longer than the load arm.
Chapter 4: Refraction of Light
| Formula | Quantity | SI Unit | Notes |
|---|---|---|---|
| n = sin i / sin r | Refractive index (Snell's law) | No unit | i = angle of incidence, r = angle of refraction |
| n = c / v | Absolute refractive index | No unit | c = speed of light in vacuum, v = speed in medium |
| ₁n₂ = n₂ / n₁ | Relative refractive index | No unit | From medium 1 to medium 2 |
| ₁n₂ = v₁ / v₂ | Relative RI (speed form) | No unit | v₁ = speed in medium 1 |
| 1/f = 1/v − 1/u | Lens formula | — | Sign convention: distances measured from optical centre |
| m = v / u | Magnification (linear) | No unit | m = hi/ho = v/u |
| m = Image size / Object size | Magnification | No unit | Positive = erect, Negative = inverted |
| P = 1 / f | Power of lens | Dioptre (D) | f in metres. Convex → +ve, Concave → −ve |
| P = P₁ + P₂ | Combined power | Dioptre (D) | For thin lenses in contact |
| sin C = 1 / n | Critical angle | — | C = critical angle for total internal reflection |
Sign convention reminder (New Cartesian):
- All distances measured from the optical centre.
- Distances in the direction of incident light → positive.
- Distances opposite to incident light → negative.
- Heights above principal axis → positive, below → negative.
Board examiners deduct marks if you don't mention which sign convention you're using. Always write "Using New Cartesian sign convention" at the start of your solution. For more on how to solve physics numericals without fear, check our detailed guide.
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Chapter 5: Sound
| Formula | Quantity | SI Unit | Notes |
|---|---|---|---|
| v = fλ | Wave equation | m/s | v = speed, f = frequency, λ = wavelength |
| v = d / t | Speed of sound | m/s | d = distance, t = time |
| f = 1 / T | Frequency | Hertz (Hz) | T = time period in seconds |
| Minimum distance for echo = v × t / 2 | Echo condition | m | t = 0.1 s (persistence of hearing), so d = v × 0.1 / 2 |
| At 20°C in air: d = 340 × 0.1 / 2 = 17 m | Minimum echo distance | m | Temperature dependent |
| Range of audibility: 20 Hz to 20,000 Hz | Human hearing range | Hz | Below 20 Hz = infrasonic, above 20 kHz = ultrasonic |
| Speed of sound: Solid > Liquid > Gas | Comparative speeds | — | Sound needs a medium; cannot travel in vacuum |
| v ∝ √T | Speed and temperature | — | Speed of sound increases with temperature |
Exam favourite: "A person standing between two parallel cliffs claps. He hears the first echo after 1.5 s and the second echo after 2.5 s. Find the distance between the cliffs." These problems always use v = d/t and the echo formula.
Chapter 6: Current Electricity
| Formula | Quantity | SI Unit | Notes |
|---|---|---|---|
| V = IR | Ohm's law | — | V in volts, I in amperes, R in ohms |
| R = V / I | Resistance | Ohm (Ω) | From Ohm's law |
| R = ρl / A | Resistance (material form) | Ohm (Ω) | ρ = resistivity, l = length, A = cross-sectional area |
| ρ = RA / l | Resistivity | Ω·m | Property of material, independent of dimensions |
| I = Q / t | Current | Ampere (A) | Q = charge in coulombs, t = time in seconds |
| Series: R_total = R₁ + R₂ + R₃ | Total resistance (series) | Ohm (Ω) | Current same through all, voltage divides |
| Parallel: 1/R_total = 1/R₁ + 1/R₂ + 1/R₃ | Total resistance (parallel) | Ohm (Ω) | Voltage same across all, current divides |
| For 2 resistors in parallel: R = R₁R₂ / (R₁ + R₂) | Shortcut | Ohm (Ω) | Product over sum rule |
| EMF = V + Ir | Internal resistance | Volt (V) | r = internal resistance of cell |
| V = EMF − Ir | Terminal voltage | Volt (V) | V < EMF when current flows |
Common mistake: Students forget that in a series circuit, current is the same everywhere — so if asked "find current through R₂", it's the same as total current. In parallel, voltage is the same across each branch.
Chapter 7: Electrical Power and Household Circuits
| Formula | Quantity | SI Unit | Notes |
|---|---|---|---|
| P = VI | Electrical power | Watt (W) | Basic power formula |
| P = I²R | Power (current form) | Watt (W) | When V is unknown |
| P = V²/R | Power (voltage form) | Watt (W) | When I is unknown |
| H = VIt = I²Rt | Heat produced (Joule's law) | Joule (J) | H = electrical energy converted to heat |
| E = P × t | Electrical energy consumed | J or kWh | If P in kW and t in hours → E in kWh |
| 1 kWh = 1 unit | Commercial unit of energy | — | Electricity bills use kWh |
| Cost = Units consumed × Rate per unit | Electricity bill | ₹ | Units = kW × hours |
| Fuse rating > Normal current of appliance | Fuse selection | Ampere | But not too much higher — next standard value |
Household Circuit Key Facts
| Concept | Detail |
|---|---|
| Domestic supply | 220 V, 50 Hz AC in India |
| Colour coding (new) | Live = Brown, Neutral = Light Blue, Earth = Green/Yellow stripe |
| Colour coding (old) | Live = Red, Neutral = Black, Earth = Green |
| Earthing purpose | Prevents electric shock by providing low-resistance path to ground |
| Short circuit | Live and neutral touch → very high current → fuse blows |
| Overloading | Too many appliances on same circuit → current exceeds fuse rating |
The board exam answer writing guide explains how to present circuit diagram numericals for maximum marks — always draw the circuit, label all values, and box your final answer.
Chapter 8: Calorimetry
| Formula | Quantity | SI Unit | Notes |
|---|---|---|---|
| Q = mcΔT | Heat energy | Joule (J) | m = mass, c = specific heat capacity, ΔT = change in temperature |
| c = Q / (mΔT) | Specific heat capacity | J/(kg·°C) or J/(kg·K) | c of water = 4200 J/(kg·°C) |
| Q = mL | Latent heat | Joule (J) | L = specific latent heat, no temperature change |
| Lf (ice) = 336,000 J/kg = 336 kJ/kg | Latent heat of fusion | J/kg | Also written as 80 cal/g |
| Lv (water) = 2,260,000 J/kg = 2260 kJ/kg | Latent heat of vaporisation | J/kg | Also written as 540 cal/g |
| Heat lost = Heat gained | Principle of calorimetry | — | In an insulated system (no heat loss to surroundings) |
| 1 calorie = 4.186 J ≈ 4.2 J | Calorie to Joule | — | Mechanical equivalent of heat |
Numerical strategy: Calorimetry problems often involve mixing hot and cold substances. Write "Heat lost by hot body = Heat gained by cold body," then expand both sides using Q = mcΔT. If a phase change is involved (ice melting), add the mL term. Students often forget to include the latent heat step when ice is melting — this costs 2 marks.
Chapter 9: Radioactivity
| Formula | Quantity | SI Unit | Notes |
|---|---|---|---|
| E = mc² | Mass-energy equivalence | Joule (J) | c = 3 × 10⁸ m/s. Einstein's equation |
| N = N₀ × (½)ⁿ | Remaining nuclei after n half-lives | — | N₀ = initial number, n = number of half-lives |
| n = t / T½ | Number of half-lives | — | t = total time, T½ = half-life |
| Mass number (A) = Protons + Neutrons | Mass number | — | Also called nucleon number |
| Atomic number (Z) = Number of protons | Atomic number | — | Defines the element |
| Alpha decay: ᴬ_Z X → ᴬ⁻⁴_(Z−2) Y + ⁴₂He | Alpha emission | — | Mass number decreases by 4, atomic number by 2 |
| Beta decay: ᴬ_Z X → ᴬ_(Z+1) Y + ⁰₋₁e | Beta emission | — | Neutron → proton + electron. A unchanged, Z increases by 1 |
| Gamma emission: No change in A or Z | Gamma ray | — | Only energy is released, no particle change |
Properties Comparison Table
| Property | Alpha (α) | Beta (β) | Gamma (γ) |
|---|---|---|---|
| Nature | Helium nucleus (⁴₂He) | Fast electron (⁰₋₁e) | Electromagnetic wave |
| Charge | +2 | −1 | 0 |
| Mass | 4 u | 1/1836 u | 0 |
| Penetrating power | Least (stopped by paper) | Medium (stopped by aluminium) | Highest (stopped by thick lead) |
| Ionising power | Highest | Medium | Least |
| Speed | ~5–7% of c | Up to 90% of c | Speed of light (c) |
| Deflection in electric/magnetic field | Deflected (less) | Deflected (more, opposite direction) | Not deflected |
How to Use This Formula Sheet
- Print or screenshot this page. Keep it next to your study desk.
- One chapter per day. Read formulas → close the sheet → write them from memory. Repeat until you can write all formulas for that chapter without looking.
- Attach units. Every time you write a formula, write the SI unit next to it. ICSE examiners deduct 0.5 marks for missing units.
- Solve 5 numericals per chapter after memorizing formulas. Use Selina textbook exercises as your primary source.
- Revise weekly. By exam week, you should be able to write all 80+ formulas in under 30 minutes.
For a broader study strategy, the how to study smart, not hard guide covers spaced repetition and active recall techniques that work well for formula memorization.
Common Unit Conversion Mistakes That Cost Marks
| Mistake | Correct Conversion | Marks Lost |
|---|---|---|
| Writing mass in grams instead of kg in F = ma | 1 g = 0.001 kg | 1 mark |
| Using cm for length in R = ρl/A | 1 cm = 0.01 m, 1 cm² = 1 × 10⁻⁴ m² | 1–2 marks |
| Forgetting to convert mm² to m² for area | 1 mm² = 1 × 10⁻⁶ m² | 1 mark |
| Writing temperature in Celsius for gas laws | Convert to Kelvin: K = °C + 273 | 1 mark |
| Using kWh where Joules are needed (or vice versa) | 1 kWh = 3.6 × 10⁶ J | 0.5–1 mark |
| Writing power of lens in cm⁻¹ instead of m⁻¹ | P = 1/f where f is in metres | 1 mark |
| Confusing mA with A | 1 mA = 0.001 A | 0.5 mark |
| Not converting cal to J | 1 cal = 4.2 J | 1 mark |
Golden rule: Before substituting any value into a formula, check that every quantity is in SI units. Write the conversion step explicitly — examiners award marks for showing the conversion.
Frequently Asked Questions
How many formulas are there in ICSE Class 10 Physics?
There are approximately 80–90 formulas across 9 chapters in ICSE Class 10 Physics. The chapters with the most formulas are Current Electricity (10+), Refraction of Light (10+), and Machines (10+). Every formula listed in the Selina Concise Physics textbook is fair game for the board exam.
Which chapter carries the most marks in ICSE Physics?
Current Electricity and Refraction of Light are typically the highest-scoring chapters, together carrying roughly 25–30 marks out of 80. Machines and Work, Energy & Power follow closely. The CISCE does not publish an official weightage, but analysis of past papers from 2020–2026 consistently shows this pattern.
Do I need to memorize derivations or just the final formulas?
For ICSE, you need both. Derivation-type questions appear in Section B (long answers) for chapters like Refraction (lens formula derivation), Machines (proving η = MA/VR × 100), and Current Electricity (deriving series and parallel resistance formulas). The final formula alone is not enough for 4–5 mark questions.
What sign convention should I use for the lens formula?
Use the New Cartesian Sign Convention. All distances are measured from the optical centre of the lens. Distances in the direction of incident light are positive, opposite are negative. ICSE board papers explicitly expect this convention — always mention it at the start of your answer.
How do I remember so many formulas without mixing them up?
Group formulas by chapter and practice writing them daily. Use the "write 3 times from memory" rule — look at the formula, close the sheet, write it 3 times. Also, associate each formula with a specific numerical problem you have solved. The connection between formula and application helps retention more than rote memorization.
Is the formula sheet different for 2027 compared to previous years?
The CISCE syllabus for 2026–27 has no major formula changes compared to 2025–26. All the formulas listed here are based on the current Selina Concise Physics textbook and the latest CISCE syllabus. If any changes are announced, they would be reflected in the official syllabus document released by CISCE.
Related Guides
- ICSE Class 10 Science Chapter Wise Marks Weightage 2027
- Board Exam Answer Sheet — Write for Maximum Marks 2027
- How to Study Physics Numericals Without Fear
- How to Study Smart, Not Hard — Indian Students
- ICSE Class 10 Maths Formulas Complete List 2027
- Board Exam Time Management — 3 Hour 180 Minute Strategy 2027
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