Physics
Fleming's Left & Right Hand Rules — LEFT for motor (force): thuMb = Motion, First finger = Field, seCond = Current. RIGHT for generator (induced current): thuMb = Motion, First = Field, seCond = induced Current. Remember "motors are sinister (left)."
Lenz's Law Direction — Induced current always opposes the change causing it. Think "nature is lazy"—it resists change. Drop magnet (N-pole down) through coil: induced field creates N-pole upward to repel.
AC Circuit Resonance — At resonance: XL = XC, impedance Z = R (minimum), current maximum, power factor = 1. Mnemonic: "RELAXED Circuit"—Resonance, Equal reactances, Low impedance, Maximum current.
Photoelectric Effect Thresholds — Remember: frequency matters, intensity doesn't (for ejection). "Frequent visits needed to enter (threshold), crowd size (intensity) irrelevant." KEmax = hf - φ; only f above threshold ejects electrons.
Right-Hand Thumb Rule (Current) — Thumb = current direction, curled fingers = magnetic field direction around wire. For solenoid: fingers curl with current flow, thumb points to N-pole.
Electromagnetic Spectrum Order — "Raging Martians Invaded Venus Using X-ray Guns": Radio, Microwave, Infrared, Visible, Ultraviolet, X-ray, Gamma. Wavelength decreases left to right; frequency/energy increases.
Nuclear Decay Alpha/Beta — Alpha (α): mass ↓4, atomic number ↓2. Beta⁻ (β): mass same, Z ↑1 (neutron → proton). Beta⁺: Z ↓1. "Alpha loses bulk; Beta flips identity."
Capacitor Charge/Voltage Relation — Q = CV (charge = capacitance × voltage). Series: same Q, voltage divides (V ∝ 1/C). Parallel: same V, charge divides (Q ∝ C). "Series shares charge; Parallel shares voltage."
Chemistry
Alcohol Reactivity Order — Primary > Secondary > Tertiary for oxidation/dehydration (E2). Reverse for SN1 reactions: 3° > 2° > 1°. "Poor Students Try; Rich Students Never"—oxidation vs substitution stability.
Lucas Test Timing — Tertiary alcohol: turbidity immediate. Secondary: 5 min. Primary: no reaction at RT. "3-2-1 Countdown"—3° instant, 2° wait, 1° never (without heat).
Aldehyde vs Ketone Tests — Aldehydes: positive Tollen's (silver mirror), Fehling's (red ppt). Ketones: negative. Mnemonic: "Aldehydes Are Generous"—they give positive tests (easily oxidized).
Biomolecule Identification — Carbohydrates: Molisch (violet ring), Benedict's (reducing sugars). Proteins: Biuret (violet, peptide bonds), Ninhydrin (blue/purple, amino acids). Fats: translucent grease spot test.
Electrochemical Series Memory — "Little Kids Caring Nothing About Zesty Interesting Copper Hats Silver Ate Gold Platinum": Li, K, Ca, Na, Al, Zn, Fe, Cu, H, Ag, Au, Pt. Reactivity decreases left to right.