Difficulty: Easy
Correct Answer: Wien’s displacement law
Explanation:
Introduction / Context:Blackbody radiation describes how ideal emitters radiate energy as a function of wavelength and temperature. Several fundamental laws describe different aspects of this emission.
Given Data / Assumptions:
Concept / Approach:Wien’s displacement law states λ_max * T = b, where b is Wien’s constant. This gives the simple inverse relationship and explains why hotter bodies radiate at shorter peak wavelengths (e.g., the Sun peaks in the visible, a hot stove in the infrared).
Step-by-Step Solution:
Identify the target: relation between peak wavelength and temperature.Recall the formula: λ_max * T = b (b ≈ 2.898 × 10^−3 m·K).Conclude the governing law: Wien’s displacement law.Contrast with other laws: Stefan–Boltzmann relates total emissive power to T^4; Planck gives full spectral distribution; Kirchhoff relates emissivity and absorptivity at thermal equilibrium.Verification / Alternative check:Apply to two temperatures to see the shift: doubling T halves λ_max, confirming the inverse proportionality.
Why Other Options Are Wrong:
Common Pitfalls:Confusing total emissive power (Stefan–Boltzmann) with the wavelength of maximum emission (Wien’s).
Final Answer:Wien’s displacement law
Discussion & Comments