Comparing intensity and distance for identical vs similar light sources

[dranseth]

Homework Statement

Two identical stars have intensity readings in a 40 to 1 ratio. Calculate the ratio of their distances.

Two similar lights are at distances in a ratio of 8 to 785. Calculate the ratio of intensities.


All I want to know is if I use E1D1^2=E2D2^2 or I1/D1^2=I2/D2^2. I'm quite sure I use E1D1^2=E2D2^2 for both. For the first one because they stars are the exact same, and for the second one because they are similar?

 

[olgranpappy]

you'll have to tell us what E, D, and I are.

 

[dranseth]

E= illumination
D=distance
I=intensity