# Voltage Regulation Using Zener Diode MCQ’s

This set of Electronic Devices & Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Voltage Regulation Using Zener Diode”.

1. The limiting value of the current resistor used in a Zener diode (when used as a regulator)
a) (R)min=[(Vin)max + VZ/R
b) (R)min=[(Vin)max-VZ]/R
c) (R)min=[(Vin)max-VZ]R
d) (R)min=[(Vin)max+ VZ]R

2. When the regulation by a Zener diode is with a varying input voltage, what happens to the voltage drop across the resistance?
a) Decreases
b) Has no effect on voltage
c) Increases
d) The variations depend on temperature

3. The percentage voltage regulation (VL) is given by_________
a) (VNL-VL)/VNL*100
b) (VNL+VL)/VNL*100
c) (VNL-VL)/VL*100
d) (VNL+VL)/VL*100

4. In the given limiter circuit, an input voltage Vi=10sin100πt is applied. Assume that the diode drop is 0.7V when it’s forward biased. The zener breakdown voltage is 6.8V.The maximum and minimum values of outputs voltage are _______

a) 6.1V,-0.7V
b) 0.7V,-7.5V
c) 7.5V,-0.7V
d) 7.5V,-7.5V

5. Determine the minimum value of load resistance that can be used in the circuit with (IZ)Min=3mA. The input voltage is 10V and the resistance R is 500Ω. The Zener diode has a VZ=6V 0and (IZ)MAX=90mA.
a) 1KΩ
b) 2.4KΩ
c) 1.2KΩ
d) 3.6KΩ

6. A transistor series regulator has the following specifications: VIN=15V, VZ=8.3V, β=100, R=1.8KΩ, RL=2KΩ. What will be the Zener current in the regulator circuit?
a) 4.56mA
b) 3.26mA
c) 4.56mA
d) 3.68mA

7. Determine the maximum and minimum values of load current for which the Zener diode shunt regulator will maintain regulation when VIN=24V and R=500Ω. The Zener diode has a VZ=12V and (IZ)MAX=90mA.
a) 40mA, 0mA respectively
b) 36mA, 5mA respectively
c) 10mA, 6mA respectively
d) 21mA, 0mA respectively

8. A Zener regulator has to handle supply voltage variation from 19.5V to 22.5V. Find the magnitude of regulating resistance, if the load resistance is 6KΩ. The Zener diode has the following specifications: breakdown voltage =18V, (IZ)Min=2µA, maximum power dissipation=60mW and Zener resistance =20Ω.
a) 0 < R < 500Ω
b) 77.8 < R < 500Ω
c) 77.8 < R < 100Ω
d) 18 < R < 500Ω

9. When is a regulator used?
a) when there are small variations in load current and input voltage
b) when there are large variations in load current and input voltage
c) when there are no variations in load current and input voltage
d) when there are small variations in load current and large variations in input voltage

10. A transistor in a series voltage regulator acts like a variable resistor. The value of its resistance is determined by _______
a) emitter current
b) base current
c) collector current
d) it is not controlled by the transistor terminals