Final answer:
Electrons flow from the negative terminal to the positive terminal in a closed circuit due to the potential difference between the terminals, which is consistent with the electron flow theory, although conventional current flow is considered in the opposite direction for circuit analyses.
Step-by-step explanation:
The question of whether electrons flow from the negative terminal to the positive terminal pertains to the concept of electric current and circuits. The answer to the question is a. Yes, always. In a closed circuit, the electrons flow from the negative terminal through the conducting path and into the positive terminal. This is due to the potential difference between the terminals; electrons move from a lower potential (negative terminal) to a higher potential (positive terminal). This flow of electrons is often referred to as 'electron flow'. However, when analyzing circuits, engineers and scientists often use the convention of 'conventional current flow', which considers the current as flowing from the positive to the negative terminal, despite the actual direction of electron movement.
It is important to understand the distinction between 'conventional current flow' and electron flow. While conventional current flow is useful for most circuit analyses, in metallic wires and resistors, electrons, which are negative charges, move in the opposite direction. This is because electrons are the charge carriers in metal and the ones responsible for conducting electricity.
The law of conservation of charge is not violated in a closed circuit, as the battery continues to maintain the flow of charge without becoming charged itself. It acts as a pump for charges, maintaining the current flow through the circuit components like bulbs, resistors, etc., without any net loss or gain of charge.