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Problem 1 Easy Difficulty

(a) What is the surface temperature of Betelgeuse, a red giant star in the constellation of Orion, which radiates with a peak wavelength of about 970 nm? (b) Rigel, a bluish-white star in Orion, radiates with a peak wavelength of 145 nm. Find the temperature of Rigel’s surface.

Answer

a. 3000 \mathrm{K} \text { or } 2700^{\circ} \mathrm{C}
b. T=\overline{20,000 \mathrm{k}}

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Top Physics 103 Educators
Christina K.

Rutgers, The State University of New Jersey

Zachary M.

Hope College

Jared E.

University of Winnipeg

Meghan M.

McMaster University

Video Transcript

Okay, So this problem, we're given the, um, radiation frequency from certain stars. And then our goal is to find out how we can relate that to the temperature there on. And so we want to use Thea Wines Displacement Law to answer these. And that's equation 27.9. Which says the Lambda Max Times t go ahead and write that. So Lamda Max Times t is equal to 0.2989 times 10 to the minus two. And then what are the units on that? Um, meter Meter? Calvin? Yes, nothing special. And so if we want to solve firm T, we just want to divide both sides by Lambda Max. And then that will give us our tea. So it plugging in the first Lambda Max Waas, um, is 9 70 And then there's 1 45 Go ahead and write that down, plugging either of those in there. You got that? The temperature for this, um, higher wavelengths pan. It is 3000 Calvin. And then if it's this one is our ejecting or out putting much higher energy photons. And so, um, it's gonna have a higher temperature. And then when I calculated it to to Sig Figs, um, it was 20,000. Come in

University of Washington
Top Physics 103 Educators
Christina K.

Rutgers, The State University of New Jersey

Zachary M.

Hope College

Jared E.

University of Winnipeg

Meghan M.

McMaster University