Radiation fundamentals (Wien’s displacement): The wavelength corresponding to the peak (maximum) emissive power of a blackbody varies inversely with absolute temperature (λ_max * T = constant). The blank in “wavelength corresponding to __________” should be filled with:

Difficulty: Easy

Correct Answer: maximum energy (peak emissive power)

Explanation:

Introduction / Context:Wien’s displacement law links blackbody temperature to the spectral position of peak emission. It is often tested by asking what physical quantity defines the peak.

Given Data / Assumptions:

  • Ideal blackbody emission.
  • Absolute temperature T measured in kelvin.
  • λ_max is the wavelength at which emissive power is highest.

Concept / Approach:Wien’s displacement states λ_max * T = constant. Thus as T increases, λ_max decreases. The “peak” refers to the wavelength of maximum monochromatic emissive power, i.e., maximum energy in the spectral distribution.

Step-by-Step Solution:

Identify the required phrase: “wavelength corresponding to maximum emissive power.”Recall the inverse relation: λ_max is inversely proportional to T.Therefore the correct fill is “maximum energy (peak emissive power).”Other phrases do not represent the spectral peak that Wien’s law addresses.

Verification / Alternative check:Plot of blackbody spectral curves at various temperatures shows peak shift toward shorter wavelengths as T increases, confirming the inverse relationship.

Why Other Options Are Wrong:“Minimum energy/minimum emissive power/average” do not define the spectral peak; “net radiative exchange” is a system-level quantity, not a spectral peak descriptor.

Common Pitfalls:Confusing Wien’s law (peak position) with Stefan–Boltzmann law (total emission proportional to T^4) or Planck’s law (full spectral distribution).

Final Answer:maximum energy (peak emissive power)

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