What is Vout when Vin55V assume Vf07 in Volts Vin101010 VVI

What is Vout when Vin=5.5V (assume Vf=0.7) in Volts?

Vin(+1010-10) VVI 1K Vin (10 to-10) Vout T Zener (Vbdx5y Zener(Vbd-5V

Solution

For zener diode to work in break down region the voltage across a zener diode is equal to or greater than V_z = V_bd.

In this circuit input voltage given is V_in = 5.5 V .

V_out = V_bd + V_f = 5 + 0.7 = 5.7 V . This is when reverse zener works in break down and forward zener in conduction.

Minimum input voltage should be grater or equal to V_in   >= 5.7 V

But here input voltage is only 5.5 V . Output voltage is 5.5 V no zener action takes place and forward diode is not in conduction state.

If input voltage is greater than 5.7 V then output is 5.7 V.