Lab Blackbodyradiation

.docx

School

American Military University *

*We aren’t endorsed by this school

Course

180

Subject

Astronomy

Date

Jan 9, 2024

Type

docx

Pages

Uploaded by student1673

Lab: Blackbody Radiation and Greenhouse Effect Much of the light we see comes from atoms and molecules, which are so hot they vibrate and collide with high-energy motion. Every time an atom changes the direction it is moving, the acceleration of electrons at the exterior of the atom causes light to be emitted. Objects at temperatures like the surface of the sun emit light in the visible part of the spectrum. For a better understanding of what blackbody radiation is, read section 8.6 of the textbook (pp. 310–313), paying particular attention to the formula for the wavelength that is given the maximum power (p. 311) and example 8.4 which uses it. To see the relationship between temperature and frequency of sunlight and light emitted by the earth itself, open the simulation Blackbody Spectrum : https://phet.colorado.edu/sims/html/blackbody-spectrum/latest/blackbody- spectrum_en.html The graph shows the distribution of light in terms of wavelength. In this chart, the farther to the left, the higher the frequency. The vertical direction represents intensity of light. (See Figure 8.38 on p. 312.) Check the boxes labeled “Graph Values” and “Labels” to see the specific wavelength of the peak intensity and in what part of the electromagnetic spectrum the wavelength falls. Set the temperature slider so the temperature is 5800 K , about the temperature of the surface of the sun. This should be the default temperature when the simulation opens. If you’ve set the “Graph Values” check box, the simulation should identify the wavelength of the peak intensity. But we can also calculate this temperature (see Example 8.3). Record the value here : Sun: λ = _____ 0.5 __________ µm Convert this to meters : Sun: λ = __ 5 x 10 -7 _______m. (Use scientific notation). Use this to calculate the frequency of the light : f = c λ = 3 × 10 8 m s λ ; If wavelength is in meters, frequency should come out in Hertz (Hz). See Example 8.2 on p. 303 for an example of how to do this. Sun: f = _ 6 x 10 14 Hz __ Adjust the temperature to 300 K, ground temperature on a warm day. At first glance, it appears nothing is graphed for this low temperature. But if you adjust the scale of the graph, you can see the curve. At the bottom right of the graph 1

Lab: Blackbody Radiation and Greenhouse Effect are two magnifying glass icons, one + and one -. Click on the “minus magnifier” three times. Then click on the “plus magnifier” at the upper left of the graph until you can see the curve clearly (9 times) . Record the wavelength and calculate the frequency as before . Earth: λ = _ _ 9.659 ____________ µm = 9.659 x 10 -6 m Earth: f = _ 3.11 x 10 13 Hz _____________ Record the results into the following table. Temperature (K) Wavelength (m) Frequency (Hz) 5800 5 x 10 -7 6 x 10 14 300 9.659 x 10 -6 3.11 x 10 13 Review the infographic below. The entire spectrum is depicted, with illustrations as well, indicating their wavelengths when compared to physical objects. Also note the illustration indicating the regions of spectrum to which the atmosphere is mostly transparent but also to which its opaque (at the bottom). [See next page.] 2

Lab: Blackbody Radiation and Greenhouse Effect Electromagnetic Spectrum: The entire electromagnetic spectrum, running from long- wavelength, low-frequency radio waves to short-wavelength, high-frequency gamma rays. (Chaisson, 20130909, p. 66) 3

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help