Under what condition is an LED lit?

An LED (Light Emitting Diode) is lit when an electric current flows through it in the correct direction, which is from the positive terminal (anode) to the negative terminal (cathode). For this to happen, the LED must be properly oriented within the circuit, meaning that the anode is connected to the higher potential, or positive voltage, while the cathode is connected to the lower potential, or negative voltage. When the current flows through the LED in this direction, it causes the semiconductor material within the LED to emit light.

In this context, the correct option emphasizes that the arrows, which often represent the direction of conventional current flow, point towards the negative terminal when describing how electricity travels through the LED. However, this should be understood in the context that the flow starts from the positive terminal, indicating that the LED is correctly positioned to allow current to flow through it, subsequently lighting it up. Understanding this concept is essential for working with LEDs in electronics, ensuring they are properly installed and powered.