What component can stabilize voltage in a power supply?

A Zener diode is designed specifically to stabilize voltage in power supply circuits. It operates in the reverse-bias region and can maintain a constant output voltage despite variations in input voltage or load current. This ability to clamp the voltage at a predetermined level makes it an ideal choice for voltage regulation.

When connected in reverse across a power supply, the Zener diode allows current to flow when the voltage exceeds its Zener voltage, effectively shunting excess current to ground and thus keeping the output voltage stable. This characteristic is particularly invaluable in circuits where precise voltage levels are essential for the proper functioning of other electronic components.

In contrast, while capacitors can smooth out voltage fluctuations (particularly in power supply filtering applications), they do not stabilize voltage in the same way that a Zener diode does. An inductor can also help in managing current flow but does not directly address voltage stabilization. Transistors can be involved in more complex forms of voltage regulation, but they usually require additional components to function effectively in that role. Thus, the Zener diode stands out as the most effective component for the job of voltage stabilization.