In a series circuit, what is true about the current through the components?

• A. Different currents flow through each component.
• B. There is no current.
• C. The same current flows through each component.
• D. Current alternates sign in each component.

Answer: (C)

In a series circuit there is a single path for the flow of electric charge, so the same amount of charge passes through every component in that loop every second. That means the current is identical at every point along the path, even though the voltage may be divided among the components depending on their resistances. If the current were different in different parts of the loop, charges would pile up at some point, which isn’t possible in a closed circuit. So the same current flows through each component.

The other ideas don’t fit this setup: if the circuit were open or incomplete, there would be no current at all; in a series loop the current does not split into different paths, so it can’t be different from one component to the next; and in a straightforward DC series circuit the current doesn’t switch direction in each component.