2010013706

An electrical source is characterized by the electromotive force $U_e=40\mathrm{V}$ and the internal resistance $R_i=2\mathrm{\Omega }$. Determine the value of the electric current for which the appliance power will be at its maximum and determine the value of this maximum power as well. $$$$ Hint: The dependence of the power of an appliance ($P$, unit Watt ($\mathrm{W}$)) on the magnitude of the folowing current ($I$, unit Ampere ($\mathrm{A}$)) is given by the relation $P=U_{e}I-R_i{I}^2$. The source properties have a role of parameters: $U_e$ is the electromotive force and $R_i$ is the internal resistance of the source.