Voltage is a measure of electrical force, measured in the units of volts. In the water model, voltage is like the water pressure in the hose. (Location 229)
Higher voltage is more force in the flow electricity, and higher current is a larger rate of the flow of electricity, as in the amount of total electricity flowing. (Location 270)
Electrical power is easy to calculate. The power in watts is simply equal to the voltage in volts multiplied by the current in amps. So if I measure a voltage as 5 V and I measure the current flowing due to that voltage as 2 A, then the total electrical power in that circuit at the moment I measured is 10 W (5 V x 2 A = 10 W). But because power is an instantaneous measurement, that 10 W could easily change. If the current doubles to 4 A instead of 2 A, the new power in that circuit is now 20 W (5 V x 4 A = 20 W). (Location 278)
