I'm trying to define a variable with the value of the thermal constant $V_T$. The value of the thermal constant is given in Volts as $V_T = \frac{k T}{q}$, where $k$ is the Boltzmann constant and $q$ is the charge on an electron.
Why am I getting different results from the following two inputs:
k = Quantity["BoltzmannConstant"];
q = Quantity["ElementaryCharge"];
T = UnitConvert[Quantity[25, "DegreesCelsius"], "Kelvin"];
Subscript[v, t] = UnitConvert[(k T)/q, "Volts"]
Which is returning the expected value of Quantity[0.0256926, "Volts"]
.
k = Quantity["BoltzmannConstant"];
q = Quantity["ElementaryCharge"];
T = Quantity[25, "DegreesCelsius"];
Subscript[v, t] = UnitConvert[(k T)/q, "Volts"]
Which is returning the unexpected value of Quantity[0.590610, "Volts"]
.
The only difference between the two is that in the first one I convert the from Celsius to Kelvin; however, the inherent physical value is not changing. So when I convert to Volts, shouldn't I get the same result from both inputs?
UnitConvert[Quantity[25, "DegreesCelsius"], "Kelvin"]
I get298.15 K
. If it wasn't able to differentiate between absolute and non-absolute wouldn't I just get 25 K? $\endgroup$