Explanation: both variables change in the same direction. An increase in one variable leads to an increase in the other, a decrease in one lead to a decrease the another
In an electric circuit, the power delivered to a load, is just the product of the potential difference between the load terminals, times the current flowing through it, as follows:
In this case, the power is the one consumed by the cell phone = 390 mW, and the voltage the one produced by the internal energy of the battery, 3.5 V, neglecting the voltage loss at the internal resistance of the battery.
So, we can solve the above equation for the current I, as follows:
The current flowing through the cell-phone circuitry is 0.11 A.
