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

• A. The current is the same through all devices
• B. The current varies
• C. The current stops
• D. The current is doubled

Answer: (A)

In a series circuit, the same amount of current flows through every device because there is only one path for the charges to follow. Charge cannot pile up at a point, and at any junction the current in must equal the current out, so the current is identical from one device to the next. While each device can drop a different amount of voltage, the current remains the same through all of them. The overall current is determined by the source and the total resistance; adding more devices in series increases the total resistance and lowers the current, but that current is shared equally by every device along the single path. The notions of the current varying between devices, stopping, or doubling don’t fit a single closed series path.