10.2 Resistors in series and parallel  (Page 5/11)

The equivalent of the series circuit would be $R_{\text{eq}}=1.00\text{Ω}+2.00\text{Ω}+2.00\text{Ω}=5.00\text{Ω},$ which is higher than the equivalent resistance of the parallel circuit $R_{\text{eq}}=0.50\text{Ω}.$ The equivalent resistor of any number of resistors is always higher than the equivalent resistance of the same resistors connected in parallel. The current through for the series circuit would be $I=\frac{3.00\text{V}}{5.00\text{Ω}}=0.60\text{A},$ which is lower than the sum of the currents through each resistor in the parallel circuit, $I=6.00\text{A}.$ This is not surprising since the equivalent resistance of the series circuit is higher. The current through a series connection of any number of resistors will always be lower than the current into a parallel connection of the same resistors, since the equivalent resistance of the series circuit will be higher than the parallel circuit. The power dissipated by the resistors in series would be $P=1.80\text{W},$ which is lower than the power dissipated in the parallel circuit $P=18.00\text{W}.$

A river, flowing horizontally at a constant rate, splits in two and flows over two waterfalls. The water molecules are analogous to the electrons in the parallel circuits. The number of water molecules that flow in the river and falls must be equal to the number of molecules that flow over each waterfall, just like sum of the current through each resistor must be equal to the current flowing into the parallel circuit. The water molecules in the river have energy due to their motion and height. The potential energy of the water molecules in the river is constant due to their equal heights. This is analogous to the constant change in voltage across a parallel circuit. Voltage is the potential energy across each resistor.
The analogy quickly breaks down when considering the energy. In the waterfall, the potential energy is converted into kinetic energy of the water molecules. In the case of electrons flowing through a resistor, the potential drop is converted into heat and light, not into the kinetic energy of the electrons.