Plotting a suitable graph to find emissivity of tungsten It is given that: Q = pσ2πal(T^4 - t^4) Where Q is the Energy Loss Rate, p is Emissivity and T,t are the wire and room temperature. Other symbols are constant. I have data for Q and (T^4- t^4), which for simplification purposes i'll call Θ. I need to find p, which is the best way of plotting data to do this? 1/ Plotting Q against Θ -> Linear Line of Best Fit -> Gradient dQ/dΘ = pσ2πal -> (p = 0.61) 2/ Plotting lnQ against lnΘ -> Linear Line of Best Fit -> Intercept = ln(pσ2πal) -> (p = 0.052) I may be overlooking something, but i don't understand why they get different values and which is correct, or if there's a silly step in the algebra. Any help would be greatly appreciated, as i'm a bit stuck. If it could also be explained why one is more appropriate, and why the other isn't, if it isn't, that's also be helpful.