Blackbody Spectrum SIM Worksheet Basic Questions You will use the Blackbird}! 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 ot'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 K.) Answer: ii} If we observe a star spectrum and nd that the peak power occurs at the border between blue and ultraviolet light. what is the surface temperature ot'thc star? [in degrees K] Answer: b} Light bulbs operate at 25C") degrees K. i) What is the wavelength at which the most power is omitted for a light bulb operating at asoo K? Answer: ii} Explain why regular incandescent bulbs waste a lot of energy. Be sure to include your reasoning. Answer: ASTR 16 Observational Astronomy NAME: c) Investigate how the observed spectrum responds to changing temperature. Note you are only able to change temperature here, but should consider how the spectrum (power vs. color) would change if you varied other characteristics about the object. True False If the only change you make is to decrease the temperature of an object, the amount of power emitted at 1000 nm will increase in some cases. True False If the only change you make is to decrease the temperature of an object, the total amount of power emitted decreases in all cases. True False If you were to increase the surface area of a bulb filament, but leave its temperature unchanged, then a larger fraction of its total power emitted would be emitted as IR radiation . d) Use the Spectrum Simulation to investigate changes in the amount of light at visible wavelengths due to this change in temperature from 2500 K to 2000 K. i) What is the approximate ratio between the powers emitted at 500 nm at 2000 degrees K to that at 2500 degrees K, that is, the power emitted at 500 nm at 2000 degrees K divided by the amount of power at 500 nm at degrees 2500 K? Answer: ii) In question 1b, we found the wavelength for the peak power of a bulb operating at 2500 degrees K. What is the approximate peak wavelength for a bulb operating at 2000 degrees K