Final answer:
Electric current, measured in amperes, is the rate of charge flow. Current is constant in a series circuit, while in a parallel circuit, it varies depending on the resistance of each branch. Large currents move more charge in less time compared to small currents.
Step-by-step explanation:
Electric current is defined as the rate at which charge flows. It is expressed in units called amperes (A), which is equal to one coulomb of charge passing through a point in one second. The current will vary in different types of circuits. In a series circuit, the current is constant throughout because there is only one path for the current to flow. However, in a parallel circuit, the total current is the sum of the currents through each parallel branch, and more current will flow through the branches with lower resistance.
Examples of calculating currents include: (a) If a truck battery moves 720 C of charge in 4 seconds, using the formula I = Q/t, the current I is 720 C / 4 s = 180 A. (b) For a handheld calculator with a 0.300-mA current, the time t required for 1.00 C of charge to flow is calculated by rearranging the equation to t = Q/I, resulting in t = 1.00 C / 0.300 mA = 1.00 C / 0.0003 A = 3333.33 s. This illustrates how larger currents move more charge in less time, and smaller currents move less charge over longer periods.