1. The problem statement, all variables and given/known data First of all I apologise if this is in the wrong place. Anyway we have been given the task of finding out the efficiency of a solar panel, where energy from a light bulb is used to heat the water in the panel. I was just wondering if someone would just check that my physics is correct. 2. Relevant equations 1. E=mcΔT 2. Energy= power x time 3. Energy efficiency= Useful energy out/total energy in 3. The attempt at a solution This is my idea, since we know both the mass and specific heat capacity of the water, by recording the change in temperature of the water over a set period of time the energy required can be worked out using equation 1. If we then work out the power output of the bulb during that time by equation 2. we can work out the efficenicy of the panel using the 3rd equation.