Physics
Fleming's Left Hand Rule — Thumb = thrust/Force, First finger = Field (magnetic), seCond finger = Current. Point them perpendicular; quick direction recall for motors.
VIBGYOR for EM Spectrum — Violent Rajas Make Indians Uneasy; Xavier Gets Caught = Radio, Microwave, Infrared, Visible, UV, X-ray, Gamma (increasing frequency/energy order).
Right-Hand Thumb Rule — Thumb shows current direction, curled fingers show magnetic field lines around a straight conductor. Essential for Biot-Savart and Ampère's law problems.
Lens Formula Sign Convention — Object side = negative, image side = positive; distances measured from optical center. Convex lens f positive, concave negative.
LC Oscillation Frequency — f = 1/(2π√LC). Remember "Like a Clock" swings at frequency depending on L and C for resonance circuits.
Radioactive Decay N = N₀e^(-λt) — After one half-life t₁/₂, exactly half remains; after two half-lives, one-quarter remains. Quick mental calculation trick for decay problems.
XL increases, XC decreases — Inductive reactance XL = 2πfL rises with frequency; capacitive reactance XC = 1/(2πfC) falls with frequency. Opposite behaviors for AC circuits.
Chemistry
HONC 1234 Rule — Hydrogen forms 1 bond, Oxygen 2, Nitrogen 3, Carbon 4 in stable organic molecules. Quick valency check for structure drawing.
LEO says GER — Loss of Electrons = Oxidation; Gain of Electrons = Reduction. Instant recall for redox reactions and electrochemistry.
Lucas Test Reactivity — 3° alcohol reacts immediately (turbidity in minutes), 2° in 5 minutes, 1° doesn't react at room temperature with Lucas reagent (ZnCl₂/HCl).
s-p-d-f Orbital Shapes — s = Sphere, p = dumb-bell/Peanut, d = Double dumb-bell, f = Flower-like (complex). Memorize for electron configuration and hybridization.
Aufbau: 1s 2s 2p 3s 3p 4s 3d — Diagonal rule: follow n+l value increasing order. When equal, lower n fills first. Essential for electronic configuration.
Aldehyde vs Ketone Tests — Fehling's/Tollens' tests: Aldehydes give positive (reduce Cu²⁺ or Ag⁺), ketones don't. RCHO oxidizes, R₂CO doesn't.
Coordination Number Geometries — CN 2 = linear, CN 4 = square planar/tetrahedral, CN 6 = octahedral. Most common shapes for BCECE coordination compound questions.
Mathematics
BODMAS/PEMDAS Trap — Division and Multiplication have EQUAL priority (left to right), same with Addition and Subtraction. 6÷2×3 = 9, not 1.
Quadratic Formula Memory — x = [-b ± √(b²-4ac)] / 2a. "Negative boy, plus-minus square root, boy-squared minus four ace, over two ace."
sin/cos Exact Values — 0°,30°,45°,60°,90°: sin = √0,1,2,3,4 all over 2; cos = reverse √4,3,2,1,0 over 2. Instant recall for trigonometric calculations.
Derivative Shortcuts — d/dx(xⁿ) = nxⁿ⁻¹; d/dx(sin x) = cos x; d/dx(eˣ) = eˣ; d/dx(ln x) = 1/x. Chain rule: multiply by derivative of inside.
Integration by ILATE — For integration by parts, choose u in order: Inverse trig, Logarithmic, Algebraic, Trigonometric, Exponential. Lower priority becomes dv.
Determinant Row Operations — Swapping rows changes sign; multiplying a row by k multiplies determinant by k; adding multiple of one row to another doesn't change value.
Probability Addition Rule — P(A∪B) = P(A) + P(B) - P(A∩B). Don't forget to subtract intersection to avoid double-counting overlapping outcomes.
Biology
Kingdom Mnemonic PPAFC — Protista, Plants, Animals, Fungi, Chromista. Or "Please Play All Five Carefully" for biological classification hierarchy recall.
Mitosis Stages PMAT — Prophase, Metaphase, Anaphase, Telophase. "Please Make A Tea" for orderly recall of cell division phases.
Cranial Nerves: Oh Oh Oh — Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducens, Facial, Auditory, Glossopharyngeal, Vagus, Accessory, Hypoglossal. First letters: "On Old Olympus Towering Top A Finn And German Viewed A Hop."
Photosynthesis Light-Dark — Light reaction in thylakoid (produces ATP, NADPH, O₂); Dark reaction in stroma (Calvin cycle, produces glucose using ATP/NADPH). Location matters for MCQs.
DNA Replication 5' to 3' — Always synthesizes 5' to 3' direction. Leading strand continuous; lagging strand = Okazaki fragments (discontinuous). Remember "Leading is Easy."
Mendel's Law Order — Law of Dominance → Law of Segregation → Law of Independent Assortment. Sequential understanding for genetics problems.
Heart Blood Flow — Vena cava → Right atrium → Right ventricle → Pulmonary artery → Lungs → Pulmonary vein → Left atrium → Left ventricle → Aorta. "Very Real People Play Loud Piano Late At night."