Physics Formula Sheet

Important physics formulas for science competitive exams

Category: PHYSICS

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MATH PHYSICS CHEMISTRY RSCIT REASONING COMPUTER SCIENCE BIOLOGY ENGLISH

Formula Collection

Mechanics

Newton's Laws

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1st: Inertia, 2nd: F = ma, 3rd: Action = -Reaction

Work

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W = F × d × cosθ

Kinetic Energy

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KE = ½ mv²

Potential Energy

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PE = mgh (gravitational)

Power

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P = W/t = F × v

Linear Momentum

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p = mv, Impulse = Δp = F × t

Circular Motion

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Centripetal Force F = mv²/r, ω = v/r, T = 2π/ω

Gravitation

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F = G(m₁m₂)/r², g = GM/R², Escape velocity vₑ = √(2GM/R)

Optics

Lens Formula

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1/f = 1/v - 1/u

Magnification

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m = v/u = hᵢ/hₒ

Refractive Index

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n = c/v = sin i / sin r

Mirror Formula

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1/f = 1/v + 1/u, f = R/2

Critical Angle

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sin C = 1/n (total internal reflection)

Power of Lens

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P = 1/f (diopter), P = P₁ + P₂ (combination)

Electricity

Ohm's Law

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V = IR, R = ρL/A

Resistors in Series

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Rₛ = R₁ + R₂ + R₃ + ...

Resistors in Parallel

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1/Rₚ = 1/R₁ + 1/R₂ + 1/R₃ + ...

Power in Circuits

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P = VI = I²R = V²/R

Kirchhoff's Laws

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KCL: Sum of currents at node = 0; KVL: Sum of voltages in loop = 0

Coulomb's Law

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F = k(q₁q₂)/r², k = 9×10⁹ N·m²/C²

Electric Field

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E = F/q = kQ/r², Potential V = kQ/r

Capacitance

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C = Q/V, C = ε₀A/d (parallel plate), Energy = ½CV²

Magnetism

Magnetic Force

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F = qvB sinθ (moving charge), F = BIL sinθ (current)

Biot-Savart Law

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dB = (μ₀/4π)(IdL×r̂)/r²

Ampere's Law

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∮B·dL = μ₀Iₑₙ𝒸

Faraday's Law

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ε = -dΦ/dt (induced EMF)

Lenz's Law

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Induced current opposes the change in magnetic flux

Transformer

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Vₛ/Vₚ = Nₛ/Nₚ, P = VI (ideal: input = output)

AC vs DC

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AC: V = V₀sin(ωt), RMS = V₀/√2; DC: constant

Thermodynamics

Zeroth Law

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If A=B and B=C then A=C — thermal equilibrium

First Law

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ΔU = Q - W (internal energy change)

Second Law

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Entropy of isolated system always increases (ΔS ≥ 0)

Third Law

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Entropy approaches zero at absolute zero (0K = -273.15°C)

Gas Laws

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Boyle's: PV = const, Charles': V/T = const, Ideal: PV = nRT

Specific Heat

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Q = mCΔT, Latent Heat Q = mL

Thermal Expansion

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ΔL = L₀αΔT (linear), ΔV = V₀γΔT (volumetric)

Waves & Sound

Wave Equation

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v = fλ, T = 1/f, ω = 2πf

Doppler Effect

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f' = f(v ± v₀)/(v ∓ vₛ) — source & observer motion

Intensity

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I ∝ A² (amplitude squared), β = 10 log(I/I₀) dB

Standing Waves

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Fundamental f₁ = v/2L, nth harmonic fₙ = nf₁

Beats

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Beat frequency fᵦ = |f₁ - f₂|

Modern Physics

Photoelectric Effect

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E = hf = Φ + KEₘₐₓ, h = 6.626×10⁻³⁴ J·s

Einstein's Energy

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E = mc² (mass-energy equivalence)

De Broglie Wavelength

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λ = h/p = h/(mv)

Radioactive Decay

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N = N₀e^(-λt), Half-life t₁/₂ = ln2/λ

Nuclear Reactions

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Fission: heavy→light + energy; Fusion: light→heavy + energy

Bohr's Model

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Eₙ = -13.6/n² eV, rₙ = n² × 0.529Å

Quick Shortcuts & Tips

⚡

SI base units: 'King Henry Died By Drinking Chocolate Milk' - kilo, hecto, deca, base, deci, centi, milli

⚡

Right Hand Thumb Rule: Thumb = current direction, curled fingers = magnetic field

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Photoelectric: Light frequency must exceed threshold for electron emission

⚡

PV = nRT: Ideal gas law — R = 8.314 J/(mol·K)

How to Use This Formula Sheet

Learn, Don't Memorize

Understand the derivation and application of each formula. Knowing why a formula works is more important than memorizing it.

Practice Application

Immediately after learning a formula, solve 5-10 problems using it. This reinforces learning and builds problem-solving skills.

Create Your Own Sheet

Copy formulas you frequently forget onto a physical sheet. The act of writing helps memory retention.

Regular Revision

Review formulas weekly. Use spaced repetition: next day, after 3 days, after 1 week, then monthly.

Common Formula Mistakes to Avoid

Unit Confusion

Always check units before applying formulas. Convert all measurements to consistent units (all in meters or all in centimeters).

Formula Misapplication

Ensure you're using the right formula for the given problem type. Don't force a formula that doesn't fit the situation.

Sign Errors

Pay attention to positive/negative signs, especially in physics and coordinate geometry formulas.

Approximation Errors

When using π = 22/7 or √2 = 1.414, be consistent. Don't mix exact and approximate values in the same calculation.

Practice with Formulas

Apply Formulas

Practice questions where you can use these formulas

Quick Revision

Review key concepts along with formulas

Study Guide

Detailed explanations of formulas and concepts

Previous Year Questions

Practice with past exam questions using these formulas