Cutoff Frequency Reason
Mediumphysics
Existence of threshold frequency explained because?
Select the correct option:
Solution
Incorrect! Answer:
Energy of photons ∝ frequency
- Classical Failure: Wave theory predicted that even low-frequency light should eject electrons if intense enough (given enough time to accumulate energy).
- Quantum Reality: Einstein proposed that light consists of discrete energy packets (photons). The energy of each photon is E=hf.
- Prerequisite: An electron can only be ejected if it receives at least ϕ amount of energy from a single photon in a single interaction.
- Deduction: This necessitates a minimum frequency f0 such that hf0=ϕ. If f<f0, energy per photon is insufficient, and no emission happens regardless of intensity.
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About This Question
- Subject
- physics
- Chapter
- dual nature
- Topic
- cutoff frequency reason
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
Energy of photons ∝ frequency
- Classical Failure: Wave theory predicted that even low-frequency light should eject electrons if intense enough (given enough time to accumulate energy).
- Quantum Reality: Einstein proposed that light consists of discrete energy packets (photons). The energy of each photon is E=hf.
- Prerequisite: An electron can only be ejected if it receives at least ϕ amount of energy from a single photon in a single interaction.
- Deduction: This necessitates a minimum frequency f0 such that hf0=ϕ. If f<f0, energy per photon is insufficient, and no emission happens regardless of intensity.
This medium difficulty physics question is from the chapter dual nature, covering the topic of cutoff frequency reason. It appeared in the 2025 exam.
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