How many Physics formulas are there in Class 10?

Approximately 30–40 key formulas across 4 chapters: Light (8–10 formulas), Electricity (12–15 formulas — most important chapter), Magnetic Effects (3–4 formulas), and Sources of Energy (2–3 formulas). Electricity alone carries 40%+ of Physics marks, so master those formulas first.

Which Physics chapter is most important for Class 10 boards?

Electricity is the most important — it carries the highest marks (around 13–15 out of 27 Physics marks) and has the most numericals. Master V = IR, P = VI, and series/parallel resistance formulas. Light (Reflection & Refraction) is second most important with mirror and lens formulas.

How to remember Physics formulas for Class 10?

Best methods: (1) Write each formula with its meaning and units, (2) Solve 5 numericals per formula immediately, (3) Make a 1-page formula sheet and review daily, (4) Understand the derivation — derived formulas are easier to recall, (5) Group related formulas (all Electricity formulas together). Practice > memorisation.

Are these formulas enough for ICSE too?

Yes — ICSE Class 10 Physics covers the same core topics (Light, Electricity, Sound, Force) with similar formulas. ICSE may go slightly deeper in some areas (e.g., more on Sound and Force/Machines). The formulas listed here cover both CBSE and ICSE requirements.

Physics Formulas Class 10 — Free Chapter-Wise PDF 2026

This is your complete Class 10 Physics formula sheet. Electricity is the highest-weightage chapter — master V = IR, P = VI, and resistance formulas first. Bookmark this page and review it daily before your board exam.

Chapter 1: Light — Reflection & Refraction

Reflection (Mirrors)

Formula	Description	Units
1/v + 1/u = 1/f	Mirror formula	v, u, f in cm
m = −v/u	Magnification (mirrors)	No unit (ratio)
m = h'/h	Magnification from image/object height	No unit
f = R/2	Focal length = half of radius of curvature	cm

Sign convention (New Cartesian): All distances measured from pole. Distances in direction of incident light = positive. Against = negative. Object is always on left → u is always negative.

Refraction (Lenses)

Formula	Description	Units
1/v − 1/u = 1/f	Lens formula	v, u, f in cm
m = v/u	Magnification (lenses)	No unit
P = 1/f (in metres)	Power of lens	Dioptres (D)
n = sin i / sin r	Snell's law (refractive index)	No unit
n = c/v	Refractive index = speed of light in vacuum / speed in medium	No unit
n₂₁ = n₂/n₁	Relative refractive index	No unit

Remember: Convex lens: f is positive. Concave lens: f is negative. Power of convex lens = positive D. Power of concave lens = negative D.

Chapter 2: Electricity (Highest Weightage)

Basic Formulas

Formula	Description	Units
V = IR	Ohm's law (Voltage = Current × Resistance)	V (volts), I (amperes), R (ohms Ω)
I = Q/t	Current = Charge / Time	A = C/s
R = ρL/A	Resistance depends on length, area, and resistivity	Ω = Ω·m × m / m²

Series & Parallel Circuits

Property	Series	Parallel
Current	Same through all: I = I₁ = I₂ = I₃	Divides: I = I₁ + I₂ + I₃
Voltage	Divides: V = V₁ + V₂ + V₃	Same across all: V = V₁ = V₂ = V₃
Resistance	R = R₁ + R₂ + R₃	1/R = 1/R₁ + 1/R₂ + 1/R₃

Power & Energy

Formula	Description	Units
P = VI	Power = Voltage × Current	Watts (W)
P = I²R	Power (using current and resistance)	W
P = V²/R	Power (using voltage and resistance)	W
H = I²Rt	Heat produced (Joule's law of heating)	Joules (J)
E = P × t	Electrical energy consumed	J or kWh
1 kWh = 3.6 × 10⁶ J	1 unit of electricity	—

Electricity tip: Most board numericals use V = IR and P = VI together. Always write: Given → Formula → Substitution → Answer with units. Step marks are generous — even if the final answer is wrong, you get marks for correct formula and substitution.

Practise Physics numericals

Super Tutor has chapter-wise Physics problems for Class 10 — Electricity, Light, and more. Solve with step-by-step solutions.

Start Physics Practice — Free

Chapter 3: Magnetic Effects of Electric Current

Formula / Rule	Description
Right-hand thumb rule	Thumb = current direction, curled fingers = magnetic field direction around wire
Fleming's left-hand rule	Forefinger = field (B), Middle = current (I), Thumb = force/motion. For electric motor.
Fleming's right-hand rule	Forefinger = field, Thumb = motion, Middle = induced current. For generator.
V = V₀ sin ωt	AC voltage equation (conceptual — not for numericals)
Transformer: V₁/V₂ = N₁/N₂	Voltage ratio = turns ratio

Key devices: Electric motor (Fleming's left-hand rule), Generator (Fleming's right-hand rule), Transformer (step-up: N₂ > N₁, step-down: N₂ < N₁).

Chapter 4: Sources of Energy

Concept	Key Facts
Calorific value	Energy released per kg of fuel. LPG: 55,000 kJ/kg, Wood: 17,000 kJ/kg, Coal: 25,000 kJ/kg
Solar cell efficiency	Typically 15–20%. Made of silicon.
Nuclear fission	E = mc² — small mass → enormous energy. 1 kg uranium = energy of 20,000 tonnes coal.
Wind energy formula	P ∝ v³ (power proportional to cube of wind speed)

Quick Revision Tips

Print this page or write these formulas by hand. Review every morning (15 minutes).
After each formula, solve 3 numericals. Reading ≠ learning. Solving = learning.
On exam day: Write top 10 formulas on your rough sheet in the first 2 minutes.
Always include units in your answer. Missing units = −0.5 marks per numerical.
Draw circuit diagrams neatly for Electricity questions — 1–2 marks for correct diagram.
Draw ray diagrams for Light questions — use ruler, label all points (F, C, P, O, I).

Formulas based on NCERT Class 10 Science (2025–2026 syllabus). Applicable for CBSE and ICSE boards. Some ICSE-specific formulas (Force, Machines, Sound) not included here — refer to your textbook for those. Last updated: February 2026.

Physics Formulas for Class 10 — Complete Formula Sheet 2026