# Tungsten Wire Heat discipation

Background Information: I'm doing an experiment in which I place a bare tungsten wire in to various liqids, to measure a coefficient $\alpha$ in the equation $$Power Dissipated = \alpha * \Delta T$$ I was also given the equation: $$R=R_0*(1+0.0045 \Delta T)$$ I decided to measure $R_0$ at a low voltage and current to stop the wire from heating up. Then I placed it in the liquid and measured the current going through the wire for a variety of voltages.

Originally I planed the substitute $Power Dissipated = V*I$ and obtain $R$ from the tangent of a V-I graph (can't use Ohms Law because the situation isn't ohmic) Unfortunately once I have substituted the values into the formulae I got a different value for every data point (all in the same range 10^-7). It made me wonder is there an equivalent formula for non-ohmic power I'm missing or is it something else entirely?

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Have you considered that the $\Delta T$ in your power equation is not the same as the $\Delta T$ in your resistance equation unless the initial temperature of the liquid and the temperature at which you measured $R_0$ are equal? –  Pranav Hosangadi Nov 15 '13 at 7:02

You need to measure $V$ and $I$, then calculate $R$ and use the second equation to calculate the temperature of the wire. Assuming you have a thermometer in your liquid you can now calculate the $\Delta T$ to use in your first equation.