Practice portal › Dual Nature of Matter and Radiation › Conceptual and Statement Questions on the Photoelectric Effect

What is the order of the strong electric field that must be applied to a metal so that electrons can be pulled out of the metal?

Asked in GSEB Board July 2023 · Conceptual points of the photoelectric effect

• (1) 10² V cm⁻¹
• (2) 10⁶ V cm⁻¹
• (3) 10⁴ V cm⁻¹
• (4) 10⁸ V cm⁻¹

Step-by-step solution

Why the other options are wrong

• (1) No single slip gives 10² V cm⁻¹. It equals 10⁴ V m⁻¹, ten thousand times weaker than the 10⁸ V m⁻¹ that field emission needs.
• (3) Comes from dividing 10⁸ V m⁻¹ by 10⁴, as if converting square metres to square centimetres. One metre is 100 cm, so divide by 10².
• (4) This is the textbook figure 10⁸ with its unit changed from V m⁻¹ to V cm⁻¹ without converting; 10⁸ V cm⁻¹ is 100 times too strong.

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