Physics
Resistor color code — *B*lack *B*rown *R*ed *O*range *Y*ellow *G*reen *B*lue *V*iolet *G*rey *W*hite (0-9). Mnemonic: "Bad Beer Rots Our Young Guts But Vodka Goes Well" for resistance values.
Right-hand thumb rule — Thumb = current direction, curled fingers = magnetic field direction around a wire. For force on conductor: First finger = Field, seCond = Current, thuMb = Motion/force (Fleming's left-hand rule).
Lens/mirror formula sign convention — All measurements from pole/optical center: distances with light direction are positive, against are negative. Real images are positive side, virtual negative. Concave mirror/convex lens have positive focal lengths.
EM spectrum frequency order — "Religious Men In Varanasi Use Xylophone Guitars Constantly" = Radio, Microwave, Infrared, Visible, UV, X-ray, Gamma (increasing frequency, decreasing wavelength).
Projectile maximum range — Launch angle of 45° gives maximum range on level ground. Range formula: R = u²sin(2θ)/g. Remember: sin(90°) = 1 is maximum, so 2θ = 90° means θ = 45°.
Thermodynamic processes — Isothermal: Temperature constant (PV = constant). Adiabatic: No heat exchange (PVᵞ = constant). Isobaric: Pressure constant. Isochoric: Volume constant. Remember "I-A-I-I" pattern.
Chemistry
Electronegativity order — F O N Cl are top four: Fluorine (4.0) > Oxygen (3.5) > Nitrogen (3.0) > Chlorine (3.0). Mnemonic: "Foxes Only Nibble Clovers" for most electronegative elements.
Amino acids classification — Essential amino acids: PVT TIM HALL = Phe, Val, Trp, Thr, Ile, Met, His, Arg, Leu, Lys. These must come from diet, body cannot synthesize.
d-block filling order — For transition elements, 4s fills before 3d, but 4s empties *first* during ionization. Example: Fe is [Ar]3d⁶4s², but Fe²⁺ is [Ar]3d⁶ (not 3d⁴4s²).
Periodic table groups — Group 1: lkali, Group 2: lkaline arth, Group 17: alogens ("salt-formers"), Group 18: oble gases. Reactivity: Group 1 increases down, Group 17 decreases down.