What is forward bias in a diode?

Forward bias in a diode refers to the condition where the positive terminal of a power supply is connected to the p-type material (anode) of the diode, and the negative terminal is connected to the n-type material (cathode). This configuration allows for current to flow through the diode, as it reduces the barrier potential that typically inhibits current flow in the reverse bias condition.

In forward bias, the applied voltage overcomes the junction potential barrier, enabling charge carriers—holes from the p-side and electrons from the n-side—to recombine at the junction, thus allowing current to pass through the diode efficiently. This defines the operational state of a diode when it is in forward bias, confirming that current flow is permitted, which aligns with the correct answer.

The other options describe conditions or aspects that do not accurately reflect the forward bias condition. For example, the prevention of current flow and states of non-conductivity relate to reverse bias and cutoff conditions, while electron accumulation refers to behaviors in specific regions of the diode but does not define forward bias itself.