Master Mnemonics for PH-01

1. "FINE" — What frequency controls vs what intensity controls

• Frequency controls → Free energy (KE_max), First emission (threshold), Force-to-stop ($V_{0}$)
• Intensity controls → Incoming count (number of photoelectrons), In-circuit current (photocurrent, saturation)
• "Frequency is Fine (precise); Intensity is just Income (quantity)"

2. "Slope Secret: K for Key, V for Valve"

• KE_max vs ν graph slope = h (Planck's constant) — K remembers h directly
• V_{0} vs ν graph slope = h/e — $V_{0}$ needs the charge e as denominator
• "KE-slope = h; $V_{0}$-slope = h/e — one step further divided by e"

3. "HEAVY is HARD to Wave" (de Broglie mass rule)

• Heavy particle → hard to make wave → shorter wavelength
• λ = h/mv → bigger m → smaller λ
• Electron (feather-light) waves; Elephant (heavy) barely waves
• For same V: λ ∝ 1/√m → λ_e/λ_p = √(m_p/m_e) ≈ 43

4. "hc = 1240 eV·nm — The Magic Number"

• 1-2-4-0 → "One-Two-Four-Zero" = your golden ticket for quick photon energy
• E(eV) = 1240/λ(nm); λ_{0}(nm) = 1240/φ(eV)
• "1240: multiply or divide and everything converts in seconds"

5. "DGN54 — Davisson-Germer Result"

• Davisson-Germer experiment, Nickel crystal, 54 V, 50° scattering angle
• "DaGerN-54-50" = the four numbers to memorise for Davisson-Germer MCQs

6. "STOP — What stops the current?"

• Stopping potential $V_{0}$ = (hν − φ)/e
• Threshold frequency ν_{0} = φ/h — stops emission entirely
• Only frequency matters for both
• Photocurrent = 0 at −$V_{0}$; current never stops below threshold regardless of intensity