A simple circuit is solved and power absorbed or supplied by each element is determined. KCL as well as Ohm's law are used in solving the circuit. positive sign convention is used in determining element powers. It is shown and discussed how a source, here current source, can be neither absorbing or supplying power. It is also mentioned that resistors are passive elements and always absorb power/energy.
A DC resistive circuit consisting of one voltage source and one current source and three resistors is solved using source definition, KCL and KVL.
A simple circuit with two voltage sources and two resistors solved using only KVL.