Question

When the regulation by a Zener diode is with a varying input voltage, what happens to the voltage drop across the resistance?

(a) Decreases

(b) Has no effect on voltage

(c) Increases

(d) The variations depend on temperature

The question was asked in exam.

The question is from Voltage Regulation Using Zener Diode topic in chapter Application of Diodes of Electronic Devices & Circuits

Answer 1

Right answer is (c) Increases

To explain I would say: When the input voltage varies, the input current also varies. This makes more current to flow in the diode. This increase in the current should balance a change in the load current. Hence the voltage drop increases across the resistor.