Max wavelength of radiation.... In the first part of this problem, you\'ll find
ID: 297808 • Letter: M
Question
Max wavelength of radiation....
In the first part of this problem, you'll find an important result for the effect of greenhouse gases. In problem 1, you've found the wavelength of the maximum radiation of the Sun - and clearly that's also the wavelength at which Earth absorbs most energy. You'll see that the maximum of Earth's radiation is at different wavelength. Greenhouse gases are transparent for the wavelengths of maximum solar radiation, but they absorb energy at the wavelengths at which the Earth's surface radiates energy back to the space. In effect they act as a blanket that lets the heat in, but won't let it out. We'll discuss this in more detail later in connection with the Earth's climate. If surface of the Earth is at temperature of 20 degree C, what is the maximum wavelength of its radiation spectrum? Don't forget to convert Celsius degrees to Kelvins! In which part of the spectrum is that wavelength? In second part of this problem, you'll find an important result in cosmology - we will discuss this later in the semester. Cosmic background radiation has a black-body form with the effective temperature of 2.73K. What is the wavelength of its maximum radiation? In which part of the spectrum is that?Explanation / Answer
a) using weins disploacement law lambda=b/T where b= constant proportionality equal to 2.8977729(17)*10^-3mK
lambda max= [2.898*10^3mK] / [293.15K] = .98mm.(maximum wavelength)
It lies in the microwave region.
b)using weins disploacement law lambda=b/T where b= constant proportionality equal to 2.8977729(17)*10^-3mK
lambda max= [2.898*10^3mK] / [2.73K]=1.0615micrometers. It lies in the shortwave infrared region (maximum wavelength)