A 6.8 V Zoner diode specified at 5 mA to have Vz la 6.8 V and rz as 20 0 with la = 0.2 mA, is operated in a regulator circuit using a 20012 resistor and a 9 V supply. Estimate the knee voltage of the Zener. For no load, what is the lowest supply voltage for which the Zener remains in breakdown opera-tion? For the nominal supply voltage, what is the maximum load current for which the Zener remains in breakdown operation? For half this load current, what is the lowest supply voltage for breakdown opera-tion?