When source voltage increases in a zener diode, which of these current remains approximately constant? (A) Series current (B) Zener current (C) Load current (D) Total current

A Zener diode is a special type of diode that allows current to flow in the reverse direction when the voltage applied across the diode, called the Zener voltage, is greater than a certain breakdown voltage. In this case, the Zener diode will maintain a constant voltage across its terminals, which is useful for voltage regulation in electronic circuits.

When the source voltage increases in a Zener diode circuit, the voltage across the Zener diode will remain approximately constant if the source voltage is greater than the breakdown voltage of the Zener diode. Since the voltage across the Zener diode is constant, any changes in the source voltage will affect the series current, Zener current, and load current, while the total current will remain unchanged.

Let's evaluate each option: (A) Series current - The series current depends on the source voltage and the resistance in the circuit. When the source voltage increases, the series current will change, not remain constant. (B) Zener current - The Zener current is the current through the Zener diode. When the source voltage increases, the Zener current will change as the diode needs to maintain a constant voltage across its terminals. (C) Load current - The load current is the current flowing through the load connected to the Zener diode circuit. Since the Zener diode maintains a constant voltage across its terminals, the load current will remain approximately constant even when the source voltage increases. (D) Total current - The total current is the sum of the series current and the Zener current. Since both of these currents change when the source voltage increases, the total current will not remain constant.

Based on the analysis in Step 3, it is clear that the correct answer is (C) Load current, as it remains approximately constant when the source voltage increases in a Zener diode circuit.