An x-ray tube designed to have only thermally limited current for x-ray energies above 20 keV. Compute the beam current in a thoriated tungsten cathode as a function of cathode temperature
when the cathode area is 1 cm2. Compare the computed current, I, with the same cathode except the material for the cathode is
tungsten.
So, to solve this I know I must use the following equation:
I = C * A * T ^2 *exp(−11600 Ew/T)
c for a thoriated tungsten is 3x10^4 and Ew= 2.63, but how do I find T in order to use this equation?
but temperature is not given

Question

An x-ray tube designed to have only thermally limited current for x-ray energies above 20 keV. Compute the beam current in a thoriated tungsten cathode as a function of cathode temperature
when the cathode area is 1 cm2. Compare the computed current, I, with the same cathode except the material for the cathode is
tungsten.
So, to solve this I know I must use the following equation:
I = C * A * T ^2 *exp(−11600 Ew/T)
c for a thoriated tungsten is 3x10^4 and Ew= 2.63, but how do I find T in order to use this equation?
but temperature is not given

anonymous · Answer

In other words the question asks you to plot the intensity as a function of temperature. In this case you insert values for (T) plug it into the formula and get a value for the intensity (I). I suppose this question is wanting you to get an idea on how the intensity changes for different values of the temperature.
 
Then the next part asks you to compare that plot or graph with tungsten. I assume here that you know where to get the parameters such as C and Ew for this substance.