Practice portal › Dual Nature of Matter and Radiation › Conceptual and Statement Questions on the Photoelectric Effect
Asked in GUJCET 2025 · Conceptual points of the photoelectric effect
Idea: a strong enough electric field can drag electrons straight out of a cold metal (field emission), and NCERT puts the field needed at the order of 10⁸ V m⁻¹.
Watch the unit: this question asks for the answer in V/cm, not in V m⁻¹.
A centimetre is a hundredth of a metre, so the same field spans a hundred times fewer volts per centimetre than per metre.
10⁸ V m⁻¹ = (10⁸)/(100) V/cm = 10⁶ V/cm
So the minimum field is about 10⁶ V/cm.
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