- A common misconception is that the current is "used up" and steadily declines as it progresses through a series of resistors. That would be a violation of conservation of charge. What is actually used up is the electric potential energy of the charge carriers, some of which is delivered to each resistor.
- Explain why the current in a real circuit very slowly decreases with time compared to its initial value.
a)As current flows in the circuit, electrons leave the negative terminal and other electrons reach the positive terminal. The potential difference across the circuit gradually declines, and so the current decreases.
b)As current flows in the circuit, the internal resistance of the battery increases over time. This raises the equivalent resistance of the circuit, and the current gradually decreases.
c)As current flows in the circuit, the resistance of the resistors outside the battery gradually increases. This raises the equivalent resistance of the circuit, and the current gradually decreases.