Question

From the Zener diode circuit shown in figure, the current through the Zener diode is

• A. $34mA$
• B. $31.5mA$
• C. $36.5mA$
• D. $2.5mA$

Answer 1

Answer: (B)

Here, $R_L=5\times 10^3\Omega$,
$V_i=220V$,
Zener voltage, $V_Z=50V$

Load current, $I_L=\frac{V_Z}{R_L}$
$=\frac{50}{20\times 10^3}$
$=2.5\times 10^{-3}A$
Current through $R,I=\frac{220-50}{5\times 10^3}$
$=34\times 10^{-3}A$
Zener current,
$I_Z=I-I_L$
$=34\times 10^{-3}-2.5\times 10^{-3}$
$=31.5\times 10^{-3}A$
$=31.5mA$