# Luminostiy, Flux, Intensity definitions and meaning

I am taking astrophysics course and we are constantly talking about Luminosity,Brightness,Intensity,Flux etc. I thought that I understand the idea properly but I see now that I dont.

Intensity is the light passing through a steradian per second

$$I=E/dtd\Omega$$

Luminosity is intensity per area

$$L=E/dtdA\Omega=I/dA$$

And Flux is the Luminosity per area ?

$$F= L/4\pi r^2$$

And brightness = Flux

Are these statements true ?

I am confusing these definitions and their meanings constantly. Can someone help me to understand it better.