What is the current through the Zener diode?

CONCEPT:

When the diode is forward biased, anode positive with reference to the cathode, a positive or forward current passes through the diode and operates within the top right quadrant of its I-V characteristics curves as shown in the figure.

Similarly, when the diode is reversed biased, cathode positive with reference to the anode, the diode blocks current apart from a particularly small leakage current and operates within the lower left quadrant of its I-V characteristic curves.

Calculation:

Here resistance R₁ is acting as a series current limiting resistor and it also prevents the flow of heavy current through the Zener diode.

As 6 V appears across the Zener diode as it is in the breakdown region,

so Zener diode will act as a constant source of 6 V.

V_z = 6 V

Applying KVL in the circuit

V₁ = I × R₁ + V_z

13 = 1× 10³ × I + 6

I = (13 - 6) × 10^-3 = 7 mA.

Hence option (2) is the correct answer.