Semiconductor Electronics Materials Devices and Simple Circuits - Result Question 19
19. A zener diode, having breakdown voltage equal to $15 V$, is used in a voltage regulator circuit shown in figure. The current through the diode is
[2011M]
(a) $10 mA$
(b) $15 mA$
(c) $20 mA$
(d) $5 mA$
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Answer:
Correct Answer: 19. (d)
Solution:
- (d) Voltage across zener diode is constant.
Current in $1 k \Omega$ resistor,
(i) $1 k \Omega=\frac{15 volt}{1 k \Omega}=15 mA$
Current in $250 \Omega$ resistor,
$ \begin{gathered} (i) _{250 \Omega}=\frac{(20-15) V}{250 \Omega}=\frac{5 V}{250 \Omega} \\ =\frac{20}{1000} A=20 mA \\ \therefore() _{\text{zener diode }}=(20-15)=5 mA . \end{gathered} $
