Physics
Right-Hand Thumb Rule — Thumb = current direction, curled fingers = magnetic field direction around a straight conductor. For solenoid: fingers = current, thumb = North pole. Essential for Magnetic Effects questions.
VIROBL for Ohm's Law triangle — V=IR. Cover what you want to find: cover V, see I×R; cover I, see V/R; cover R, see V/I. Quick formula recall.
Real/Virtual Image Decision — Concave mirror: object beyond F gives real inverted image; between F and pole gives virtual erect. Convex mirror and convex lens always virtual for objects at any distance (lens exception: real when object beyond 2F).
Sign Convention Anchor — Distances measured AGAINST incident light = negative (object distance, focal length of concave). WITH incident light = positive. Heights above axis = positive, below = negative.
G-value 10 Approximation — Use g=10 m/s² for quick calculations instead of 9.8. Saves time; most UK JEEP questions accept ±2% error. For precise questions, keep 9.8.
SWAN for Wave Speed — Speed = Wavelength × Frequency (v=λν). "Swan" glides smoothly—so does wave speed calculation. Directly applicable to Sound chapter numericals.
Power-Energy-Time Triangle — P=W/t. Cover P, see W/t; cover W, see P×t; cover t, see W/P. Works identically for electrical power P=VI.
Echo Time Formula — Minimum distance for echo = 17 m (speed of sound 340 m/s, minimum distinguishable time 0.1s). Distance = (340×t)/2 where t = time interval heard.
Chemistry
OIL RIG — Oxidation Is Loss (of electrons), Reduction Is Gain. Instantly identify redox reactions in Chemical Reactions chapter. The electron-transfer memory hook.
PAN for Strong Acids — Phosphoric, Nitric (HNO₃), Sulphuric (H₂SO₄). Wait—actually SIN-P: Sulphuric, Nitric, Hydrochloric (common strong), Phosphoric (moderate). Strong bases: NaOH, KOH, Ca(OH)₂.
pH Memory: 7-Neutral, <7 Acid, >7 Base — "Lucky 7" is neutral water. Below = acidic (0-6), above = basic (8-14). Stomach acid ≈2, soap ≈10. One-digit scale, easy recall.
Valency Via First 20 — H=1, He=0; next row: Li-1, Be-2, B-3, C-4, N=3, O=2, F=1, Ne=0. Pattern: 1-2-3-4-3-2-1-0 repeats with variations. Carbon's 4 explains its compound diversity.
Methane-Ethane-Propane-Butane (MEPB) — First four alkanes: CH₄, C₂H₆, C₃H₈, C₄H₁₀. Formula CₙH₂ₙ₊₂ for alkanes. "MEPB" = syllable sequence for carbon count 1-2-3-4.
Reactivity Series: "Please Send Charlie's Monkeys And Zebras In Lead Cages Securely Guarded Properly" — Potassium, Sodium, Calcium, Magnesium, Aluminum, Zinc, Iron, Lead, Copper, Silver, Gold, Platinum. Decreasing reactivity; left displaces right.
Period = Shells, Group = Valence — Periodic table: period number = electron shells (Na in period 3 = 3 shells). Group number (old system) = valence electrons (Group 1 = 1 valence electron).
Mathematics
Divisibility by 11 — Alternating digit sum. For 2728: (2+2)−(7+8)=4−15=−11, divisible. Quick check for factors in Real Numbers.
Quadratic Formula Song Rhythm — "x equals negative b, plus-or-minus root, b-squared minus 4ac, all over 2a." Sing to rhythm; never forget x=[-b±√(b²-4ac)]/2a.
All-Silver-Tea-Cups (ASTC) — Quadrant-wise trigonometric signs. Anticlockwise from Q1: All positive, Sin positive only, Tan positive only, Cos positive only. Critical for Trigonometry.
Slope Formula: Rise over Run — m=(y₂−y₁)/(x₂−x₁). "Rise" (vertical change) divided by "Run" (horizontal). Coordinate Geometry staple; never mix up numerator/denominator.
Probability = Favorable/Total — P(E)=favorable outcomes/total outcomes. Always ≤1. For "not E": P(not E)=1−P(E). Sum of all probabilities = 1.
AP Formula: "a-plus-n-minus-1-d" — nth term aₙ=a+(n−1)d. Sing it rhythmically. Sum Sₙ=n/2[2a+(n−1)d] or n/2(first+last). Arithmetic Progression core.
Heron's Formula Triangle — Area=√[s(s−a)(s−b)(s−c)] where s=(a+b+c)/2. "Semi-perimeter times leftover three parts under root." For scalene triangles in Areas chapter.
Pythagoras Triples: 3-4-5, 5-12-13, 8-15-17 — Memorize these. Scale them (6-8-10, 9-12-15) for instant right-triangle recognition. Saves 30+ seconds per geometry problem.
Circle Area vs Circumference — Area=πr², Circumference=2πr. Remember: Area has r², circumference has r. Sector area=(θ/360)×πr², arc length=(θ/360)×2πr. Angle fraction scales both.