Measuring the Efficiency of a Light Bulb Using a Solar Panel
I don’t even know how well this will work, but I’m going to do it anyway. I’m going to use the Sun to estimate the efficiency of a small solar panel and then use that solar panel to estimate the efficiency of a light bulb. I really hope this works because I already made my students in lab attempt this measurement.
Let’s get started.
Power, Intensity, and Efficiency
Of course we need some physics background. Let’s start with a light bulb (don’t worry — I’m going to use this to get to the physics). This light bulb has a potential difference across it (ΔV in volts) and an electric current going through it (I in amps). From that, we can calculate the power consumed by the bulb as the product of the voltage and current.
Remember that this power (measured in Watts) is just the rate of change of energy (Joules per second). But what happens to this power that goes into a bulb? After the bulb has warmed up (no more increase in thermal energy) the amount of power into the bulb is equal to the output power.
