Which of the following types of linear voltage regulator operates by loading the unregulated voltage source?
Why A shunt regulator sits in parallel with the load, behind a fixed series dropping resistor. It regulates by drawing (shunting) whatever extra current is needed to hold the output voltage constant, so it deliberately loads the unregulated source. A Zener diode regulator is the classic example: when load current drops, the shunt element soaks up more current, keeping total draw roughly constant.
Watch out A series regulator is the tempting pick, but it sits in line with the load and works by varying its own voltage drop, so it passes only the current the load needs rather than loading the source.
Shunt = parallel = it eats the leftover current. Series = in line = it drops the extra voltage.