Physical Science Last Minute Revision
Quick-fire revision for BSE Telangana Class 10 Physical Science — must-know Physics formulas, Chemistry reactions, light recall, and exam tips for the final 24 hours.
Physics — Must-Know Formulas
- →Ohm's Law: V = IR · Power: P = VI = I²R = V²/R · Energy: E = Pt (watt·seconds)
- →Series: R_total = R₁ + R₂ · Parallel: 1/R = 1/R₁ + 1/R₂
- →Mirror: 1/v + 1/u = 1/f · Lens: 1/v − 1/u = 1/f · Power of lens: P = 1/f (metre)
- →Magnification (mirror): m = −v/u · Magnification (lens): m = v/u
Chemistry — Key Reactions
- →Acid + Metal → Salt + Hydrogen: Zn + H₂SO₄ → ZnSO₄ + H₂
- →Acid + Base (neutralisation): HCl + NaOH → NaCl + H₂O
- →Acid + Carbonate → Salt + CO₂ + H₂O: Na₂CO₃ + 2HCl → 2NaCl + CO₂ + H₂O
- →Thermite reaction: Fe₂O₃ + 2Al → Al₂O₃ + 2Fe (highly exothermic, used in welding)
- →Saponification: Fat/Oil + NaOH → Soap + Glycerol (ester hydrolysis in base)
Physics — Light Recall
- →Concave mirror: object beyond C → real, inverted, smaller image. Object at F → image at infinity
- →Convex mirror: always virtual, erect, diminished — used in rear-view mirrors
- →Convex lens: converging lens — used to correct hypermetropia (farsightedness)
- →Concave lens: diverging lens — used to correct myopia (nearsightedness)
Electricity — Quick Points
- →Conventional current flows from + to − (positive to negative) in external circuit
- →Ammeter is always in series · Voltmeter is always in parallel
- →1 kWh = 1000 watts × 3600 seconds = 3.6 × 10⁶ J (unit for electricity bills)
- →Heating effect of current: H = I²Rt (Joule's law of heating)
Exam Day Tips
- →For numerical problems: write formula → substitute → solve. Never skip the formula step
- →Circuit diagram questions: label all components clearly — lose marks for missing labels
- →Chemical equations: balance by inspection — H₂ + O₂ → H₂O needs balancing to 2H₂ + O₂ → 2H₂O
- →For 5-mark questions: write a definition, explanation, diagram, example, and application — that's 5 points