Physical Science Formula Sheet
Chapter-wise formula reference for TS SSC Class 10 Physical Science — every key Physics equation and Chemistry formula with variable explanations. Bookmark this before your board exam.
Physics Formulas
Chapters 1–6Mirrors (Ch. 1)
Mirror Formula
1/f = 1/v + 1/u
f = focal length, v = image distance, u = object distance. All measured from pole. Sign convention: distances in direction of incident light are positive.
Magnification
m = −v/u = h′/h
m = magnification, h′ = image height, h = object height. m < 0 means inverted image; m > 0 means erect image.
Refraction — Plane Surfaces (Ch. 2)
Snell's Law
n₁ sin θ₁ = n₂ sin θ₂
n₁, n₂ = refractive indices of medium 1 and 2; θ₁ = angle of incidence; θ₂ = angle of refraction.
Refractive Index
n = sin i / sin r = c / v
c = speed of light in vacuum (3 × 10⁸ m/s); v = speed of light in the medium.
Lenses (Ch. 3)
Lens Formula
1/f = 1/v − 1/u
f = focal length, v = image distance, u = object distance. Sign convention: distances measured from optical centre.
Magnification
m = v/u = h′/h
For lenses, m is positive for erect (virtual) images and negative for inverted (real) images.
Power of a Lens
P = 1/f (in metres)
P = power in dioptres (D); f must be in metres. Convex lens: P > 0; Concave lens: P < 0.
Combined Power
P = P₁ + P₂
When two thin lenses are placed in contact, their powers add directly.
Electric Current (Ch. 5)
Ohm's Law
V = IR
V = potential difference (volts); I = current (amperes); R = resistance (ohms).
Resistance
R = ρl/A
ρ = resistivity (Ω·m); l = length of conductor (m); A = cross-sectional area (m²).
Series Resistance
R_total = R₁ + R₂ + R₃
Total resistance is the sum of all resistors in series. Same current flows through all.
Parallel Resistance
1/R = 1/R₁ + 1/R₂ + 1/R₃
Reciprocal of total resistance equals sum of reciprocals. Same voltage across all.
Electric Power
P = VI = I²R = V²/R
P = power (watts); V = voltage (V); I = current (A); R = resistance (Ω).
Joule's Law of Heating
H = I²Rt
H = heat produced (joules); I = current (A); R = resistance (Ω); t = time (seconds).
Electromagnetism (Ch. 6)
Fleming's Left-Hand Rule
Force direction for motors
Point the forefinger in the direction of the magnetic field, the middle finger in the direction of current — the thumb points in the direction of the force (motion).
Fleming's Right-Hand Rule
Current direction for generators
Point the thumb in the direction of motion (conductor moving), the forefinger in the direction of the magnetic field — the middle finger gives the direction of induced current.
Chemistry Formulas
Chapters 7–12Chemical Reactions (Ch. 7)
Combination Reaction
A + B → AB
Two or more reactants combine to form a single product. Example: 2H₂ + O₂ → 2H₂O
Decomposition Reaction
AB → A + B
A single compound breaks down into two or more products. Example: 2H₂O → 2H₂ + O₂ (electrolytic)
Single Displacement
A + BC → AC + B
A more reactive element displaces a less reactive one from its compound. Example: Fe + CuSO₄ → FeSO₄ + Cu
Double Displacement
AB + CD → AD + CB
Ions of two compounds exchange to form two new compounds. Example: Na₂SO₄ + BaCl₂ → BaSO₄↓ + 2NaCl
Acids, Bases and Salts (Ch. 8)
pH Formula
pH = −log[H⁺]
[H⁺] = molar concentration of hydrogen ions. Acidic: pH < 7; Neutral: pH = 7; Basic: pH > 7.
Neutralisation
Acid + Base → Salt + Water
Example: HCl + NaOH → NaCl + H₂O. The salt formed depends on the specific acid and base used.
Structure of Atom (Ch. 9)
Maximum Electrons per Shell
Max electrons = 2n²
n = shell number. Shell 1 (K): 2 electrons; Shell 2 (L): 8 electrons; Shell 3 (M): 18 electrons.
Valency from Configuration
Valency = electrons in outermost shell (if ≤ 4) or 8 − outermost electrons (if > 4)
Applies to main-group elements. For noble gases, valency = 0.