Final answer:
Disconnecting a circuit from the positive terminal stops the flow of electric current by creating an incomplete circuit, ceasing the movement of electrons from the negative to the positive terminal, and consequently, any device in the circuit will cease to function.
Step-by-step explanation:
When you disconnect a circuit from its positive terminal, the circuit becomes incomplete, and the flow of electric current stops. A circuit needs to be a closed loop for current to flow. This interruption in the circuit means that charges no longer flow from the positive terminal to the negative terminal. In the specific context of a battery, when the positive and negative terminals are connected through a load (like a lightbulb), electrons flow from the negative to the positive terminal. This creates a current that allows the bulb to light up. Disconnecting the positive terminal prevents the electrons from completing the circuit, thus stopping the current and turning off the bulb. It is important to note that this does not violate the law of conservation of charge because the charges are still present but are no longer in motion due to the break in the circuit.