:<math>i(t) = L \{ v(t) \} </math>
where V(t) is the voltage across the device, i(t) is the current flowing through it and '''L''' is an operator function, which may involve differential or integral operators. Lumped devices are incorporated into the FDTD grid across two adjacent nodes in a similar manner to lumped sources. At the location of a lumped device, the FDTD solver enforces the device's governing equation by relating the device voltage and current to the electric and magnetic field components and updating the fields accordingly at every time step.
[[Image:Info_icon.png|40px]] Click here to learn more about '''[[Modeling_Lumped_Elements,_Circuits_%26_Devices_in_EM.Cube#Defining_Lumped_Loads_in_EM.Tempo | Defining Lumped Loads in EM.Tempo]]'''.