1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Calculating Luminosity (Easy Atronomy Question)

  1. Jan 24, 2013 #1
    Capella is the same temperature as our sun, but about ten times the suns diamter; it must be about_____ times as luminous as our star.

    Could someone please tell me how to solve this type of problem??

    I am aware of the formula R=sqrt(L)/Temp squared.

    But I'm not sure how to apply that here. Inserting my own made up radius of 2 for the sun and 20 for Capella, I come up with the answer being "100 times as luminous". But I fee like Im missing something...

  2. jcsd
  3. Jan 24, 2013 #2


    User Avatar
    Science Advisor
    Homework Helper

    hi zoiberg137! :smile:
    no, that's fine :smile:

    that's exactly how these "dimensional analysis" questions work …

    R2/L is a constant

    so if you multiply R by 10, you do multiply L by 100 :wink:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook