Which component effectively becomes a short when turned on, and is turned off by disconnecting the path from the anode to cathode?

The correct response highlights the behavior of a silicon controlled rectifier (SCR). When an SCR is turned on, it allows current to flow from the anode to the cathode, effectively creating a path that acts like a short circuit. This characteristic enables it to conduct substantial current through the load in various applications, such as in power control and switching.

Once the SCR is in the conducting state, it remains "on" until the current flowing through it drops below a certain threshold, known as the holding current. To turn off the SCR, it is necessary to interrupt the path from the anode to the cathode; simply cutting off the gate signal will not suffice. This feature differentiates SCRs from other semiconductor devices that may turn off with a gate signal or change in voltage.

In contrast, diodes allow current to flow in one direction but do not maintain a short circuit state after being forward-biased without an external path management. Bipolar junction transistors and field-effect transistors function differently, as they have distinct switching mechanisms and gate controls that enable them to turn off independently from the current flowing through. Understanding the operation and unique characteristics of an SCR is essential for applications involving controlled rectification and phase control in AC circuits.