Topics: Infrared, Black body, Electromagnetic radiation Pages: 3 (709 words) Published: April 22, 2013
Go to http://phet.colorado.edu/simulations/sims.php?sim=Blackbody_Spectrum and click on Run Now.

1) In this lab, you will use the Blackbody Spectrum Simulation to investigate how the spectrum of electromagnetic radiation emitted by objects is affected by the object's temperature. In this simulation, you can input the temperature and observe the spectrum of the radiation emitted. a) The temperature of stars in the universe varies with the type of star and the age of the star among other things. By looking at the shape of the spectrum of light emitted by a star, we can tell something about its average surface temperature. i) If we observe a star's spectrum and find that the peak power occurs at the border between red and infrared light, what is the approximate surface temperature of the star? (in degrees C) The temperature will be ~4000K which would be about 3276 degrees Celcius. ii) If we observe a stars spectrum and find that the peak power occurs at the border between blue and ultraviolet light, what is the surface temperature of the star? (in degrees C) The temperature would be about 7050 degrees Celcius.

b) Light bulbs operate at 2500 degrees C.
What is the wavelength at which the most power is emitted for a light bulb operating at 2500 C? The wavelength would be equal to 1000nm
ii) Explain why regular incandescent bulbs waste a lot of energy. Be sure to include your reasoning. The majority of the light emitted is at wavelengths that are longer than that, that are visible. So the power going into the light bulb that is producing non-visible light is wasted. It is wasting energy that way, so regular incandescent bulbs are inefficient.

2) In this problem we will explore the greenhouse effect by using the Greenhouse Effect Simulation available from http://phet.colorado.edu/simulations/sims.php?sim=The_Greenhouse_Effect
a) Explore the simulation.
True or False

The only effect of increasing the number of clouds...