Practice portal › Dual Nature of Matter and Radiation › Conceptual and Statement Questions on the Photoelectric Effect
Asked in GUJCET 2024 · Conceptual points of the photoelectric effect
Idea: pulling an electron straight out of a cold metal is field emission, not photoemission, and it is the applied electric field that does the work.
The field has to bend the metal's surface barrier so steeply that electrons tunnel through it, which takes a field far beyond anything in ordinary electrostatics.
NCERT puts that field at the order of 10⁸ V m⁻¹, and gives the spark plug as the everyday example.
For scale, dry air breaks down at only about 3×10⁶ V m⁻¹, which is why field emission needs a sharp tip or a vacuum.
So the minimum field is about 10⁸ V m⁻¹.
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