A black body at 20 K is found to emit maximum energy at a wavelength 14 µm. When its temperature is raised to 1000K, then wavelength at which maximum energy emitted is
Wavelength is the distance between two consecutive crests or troughs of a wave. It is commonly used to describe electromagnetic waves like light, radio, and sound. Wavelength is inversely proportional to frequency, meaning longer wavelengths have lower frequencies and shorter wavelengths have higher frequencies. It is measured in meters.
Class 11 Physics Chapter 10 Thermal Properties of Matter covers heat transfer specific heat capacity thermal expansion and calorimetry. It explains conduction convection and radiation along with the concept of thermal equilibrium. The chapter also includes laws of heat transfer and their practical applications which are essential for the CBSE Exam 2024-25.
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According to Wien’s displacement law, the wavelength at which the black body emits maximum energy varies inversely with temperature:
λ_max * T = constant
Let the initial temperature be 20 K with a wavelength of 14 µm, and the final temperature be 1000 K. Given that using Wien’s law,
λ₁ * T₁ = λ₂ * T₂
14 µm * 20 K = λ₂ * 1000 K
λ₂ = (14 µm * 20 K) / 1000 K
λ₂ = 280 µm / 1000
λ₂ = 0.28 µm
Thus, the correct answer is: 2.8 µm
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