What is apparent brightness?

Question

I need to figure this out to do some physics homework but the answers i get from google are to complicated. I need a simple answer and please include a formulae to calculate a star's apparent brightness

Answer 1

A flashlight is the same absolute magnitude if it is 0.01 m from your eye as it is when it is 10 meters from your eye.  The apparent brightness is decreased with the added distance.  Brightness or apparent magnitude falls off as the square of the distance.

Calculating the magnitude can get a bit ugly, but here is the link to the Wikipage:

http://en.wikipedia.org/wiki/Apparent_ma...

I fully realize that you wanted a simple answer, but unfortunately, the answer/technique is not so simple and it depends on the information that you are given.

I hope this helps!

Edit: Sorry, I did not answer your question--Apparent brightness is the scale of how bright an object appears to an observer on earth, regardless of the distance of the object.

Here is a way to work with apparent magnitude and absolute magntide as they relate to distance:

The huge variation in distances of individual stars from the observer on Earth (or elsewhere) requires the observed apparent magnitude (generically symbolized by m) of each star be corrected for distance to give an intrinsic brightness required for scientific comparison of the stars; defined to be equal to the apparent magnitude at the fixed distance of 10 parsecs from the star, this absolute magnitude (symbol M) is computed as

    M = 5 + m - 5log(d)   <--(base 10 log)

where d is the actual distance away in parsecs.

From: http://www.answers.com/topic/apparent-ma...