# I How can I correlate the light intensity and energy?

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1. Aug 22, 2016

### _Gandalf_

I need to know how much energy will I have for a certain intensity of ligh, I need this because I want to predict how much water will my solar oven evaporate for this light intesity (I can mesure the light intensity). I'd be very thankful if anyone helped me on this because I've searched a lot I have made no progress

2. Aug 22, 2016

### nasu

In waht unit are you going to measure the light intensity?

3. Aug 22, 2016

### _Gandalf_

In candles

4. Aug 22, 2016

### nasu

Then you will have a hard time to find the energy. The luminous intensity measured din candela depends on the wavelength of the light.
If you have a continuous spectral distribution, the intensity in candela will be given by a integral over all the wavelengths.
How are you actually measuring it? You have an instrument that gives you intensity in candela?

5. Aug 25, 2016

### _Gandalf_

Yes, I'm using and Arduin system that mesures the eletric current that the sun produces, then I use a table to convert it (actually I'm trying to make it give automatically the result in candela, buut I'm not very good at programming)

6. Aug 25, 2016

### nasu

How does the sun produce that electric current? You are using some sensor, aren't you?
Anyway, if you want to know the energy, why bother to convert to luminous intensity in candela?
I thought you already have an instrument that gives readings in candela and you want to find the energy. But your last post does not fit this scenario.

You may get better answers if you say from the beginning the complete story rather than leaving out pieces that may be essential (even if you thin they aren't).

7. Aug 25, 2016

### _Gandalf_

Ok I'll try. I can mesure the iluminance of the light, in lux, (yes, I changed the way I mesure), so I use a resistor that gives a value that I useto get value of the iluminance. Now I have the luminance and I want to convert it into energy, or something that gives me the result in W/m^2, because O want to predict how much water will my solar oven evaporate given a certain quantity of iluminance. My solar oven is composed of a aerial with more than 300 pieces of glass glued on it, I can consider it a perfect reflector.

8. Aug 25, 2016

### nasu

How is the resistor giving a value? What kind of value? And what kind of resistor?

9. Aug 26, 2016

### Staff: Mentor

Great! Can you change the way you measure to give you watts per square meter?
Can't you just use the known value for the sun's intensity? Why do you even need to measure it?

I agree with @nasu that your posts are so vague that it is difficult to help you.