Electron Emission & Photoelectric Discovery Challenge
25 NEET-standard questions on cathode rays and the electron, work function and the electron volt, thermionic, field and photoelectric emission, and the discoveries of Hertz, Hallwachs and Lenard. Answer each one. If you get it wrong, Vidya Ma’am explains it with an animated movie you can control, a slider to play with, and a step-by-step solution. Then try again.
NCERT Physics XII Part II · Ch. 11 · pp. 274–276Keys: A–D or 1–4 to answer
🧠 Formula memory tricks (open before you start)
Thomson’s balancev = E/Bundeflected beam: eE = evB, B in tesla
Electron datae/m = 1.76×10¹¹ C/kge = 1.6×10⁻¹⁹ C, m = 9.1×10⁻³¹ kg
Electron volt1 eV = 1.6×10⁻¹⁹ JKE = qV: same for electron and proton
Work functionMinimum energy to escape: φ₀depends on the metal and its surface
Three emissionsThermionic = heat · Field ≈ 10⁸ V/m · Photoelectric = lightspark plug = field emission
HallwachsElectrons leave → charge moves towards positivenegative discharges, neutral turns +, positive grows +
PhotocurrentI = N·econvert µA to A first
right first tryfixed after explanationstill to fix
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