what is the formula for luminance(lux)

how to find the light intensity?
i looked for it in the internet but i couldnt find
what is the formula to determine light intensit?
doesnt matter if the formula is in candela or luminance
help me please.
i will be having a viva test on my project
thank you

What do you mean? Your questions sounds analogous to what is the equation to find distance/mass/speed. It's something that has to be measured?

Or do you mean you want to find the intensity at distance Y given that you know the intensity at distance X? In this case intensity decreases by the distance squared. So if you are given the intensity at X meters you have to normalize it to 1 unit distance by multiplying the intensity by X^2.

Then you divide the intensity at 1 unit distance by Y^2 to find the intensity at distance Y.

You can combine X and Y in one equation to get:

[New Intensity] = [Given Intensity]*(X/Y)^2

where Y is the distance for [new intensity] and X is distance for [given intensity]

At least that's how I think it is.

Have a look at this link:
https://www.electro-optical.com/whitepapers/candela.htm
and here also:

**broken link removed**

They cover the basics as well as the relationships between the different units.