2. Active Heat Load
The general equation for active heat load dissipation is:
Qactive = V2/R = VI = I2R
Qactive = active heat load (W)
V = voltage applied to the device being cooled (V)
R = device resistance
(W) I = current through the device (A)
For example, a typical lead selenide (PbSe) infrared detector is operated at a bias voltage of 50 volts and a resistance of 0.5 megohms. Therefore, the active load is 0.005 watts.