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Photometry
Luminous intensity measurement
luminous intensity of second source (two sources bring identical illuminance to identical surfaces)
I
2
=
cd
x
cd
luminous intensity of second source (two sources bring identical illuminance to identical surfaces)
I
1
=
cd
x
cd
distance from second light source to illuminated surface
r
2
=
m
x
Å
nm
μm
mm
cm
dm
m
km
n mile
in
ft
yd
distance from first light source to illuminated surface
r
1
=
m
x
Å
nm
μm
mm
cm
dm
m
km
n mile
in
ft
yd
1. Define values of all variables, besides sought quantity
2. Change units if necessary
3. Click "Calculate"