Calculate too:
Photon mass

Photometry

Luminous intensity measurement

I₂

		x
cd

I₁

		x
cd

r₂

r₁

1. Define values of all variables, besides sought quantity
2. Change units if necessary
3. Click "Calculate"

		variables: I₂ - luminous intensity of second source (two sources bring identical illuminance to identical surfaces) I₁ - luminous intensity of second source (two sources bring identical illuminance to identical surfaces) r₂ - distance from second light source to illuminated surface r₁ - distance from first light source to illuminated surface