Photoelectric Effect Cathode Coating – Rankers Physics

Photoelectric Effects and deBroglie Equation: Practice Problem & Solution

Assertion (A): In photoelectric effect, cathode or emitter plate is usually coated with barium oxide, barium sulphide or strontium oxide. Reason (R): Coating prevents cathode from erosion.  
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Photoelectric Effects and deBroglie Equation. Understanding the underlying formula is key to arriving at the correct answer below:

Cathodes are coated with materials like barium oxide to lower their work function, enhancing photoemission efficiency. So (A) is true. Coatings can indeed prevent erosion, so (R) is also true. However, preventing erosion is not the primary reason for choosing these specific low work function materials, so (R) is not the correct explanation for (A).

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