Nate Core Practice Test

What type of current does a diode effectively allow to pass through it?

1. AC current

2. Direct current only

3. Alternating current only

4. Both AC and DC currents

The correct answer is: Direct current only

A diode is a semiconductor device that acts as a one-way valve for electrical current. It primarily allows direct current (DC) to pass through while blocking alternating current (AC). In its ideal operation, a diode only conducts electricity when the voltage across it is in the forward direction, which is typically the case with DC. AC current, on the other hand, alternates direction periodically, which means that while the diode may allow current to pass during one half of the cycle (when the voltage is positive), it will block it during the other half (when the voltage is negative). This behavior makes diodes useful in converting AC to DC, but does not allow them to effectively pass AC current as a whole. Hence, the focus of the question is on the diode's primary function, which is to facilitate the flow of DC, making "direct current only" the correct answer.