A zener regulator has an input voltage from 15 to 20 V and a load current from 5 to 20 mA. If the zener voltage is 6.8 V, what value should the series resistor have?

A zener regulator has an input voltage from 15 to 20 V and a load curr

1.	A zener regulator has an input voltage from 15 to 20 V and a load current from 5 to 20 mA. If the zener voltage is 6.8 V, what value should the series resistor have?
A.	310 Ohm
B.	400 Ohm
C.	410 Ohm
D.	550 Ohm
Answer» D. 550 Ohm