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- Subject
- Regulated D.C. Power Supplyelectrical-engineering-mcqs › regulated-d-c-power-supply
- Published
- 22 Dec 2018
- Last updated
- 28 May 2026
Explanation
Given two 15 V Zener diodes in series, the total Zener voltage is 30 V. The input voltage is 45 V, so the voltage drop across the series resistor is 45 V - 30 V = 15 V. To ensure the current does not exceed 300 mA, use Ohm's law: R = V/I = 15 V / 0.3 A = 50 ohms. Therefore, the correct series resistor value is 50 ohms.
More Regulated D.C. Power Supply MCQs
Practice related questions from the same subject.
- 1.A power supply exhibits a voltage regulation of 1%. Given that the voltage at no load is 20 V, what is the voltage when the supply is fully loaded?
- 2.What happens to the Zener current when there is no load current flowing?
- 3.A power source provides a maximum current of 0.5 A at its full-load voltage of 20 V. What is the smallest load resistance that can be safely connected to this power supply?
- 4.What effect does a Zener regulator have on the ripple voltage in a power supply?
- 5.When does the Zener diode current reach its lowest value?
- 6.If two identical 15 V Zener diodes are connected in series, what will be the total regulated output voltage?
- 7.If the alternating current (a.c.) input voltage to a regulated or standard power supply rises by 5%, what is the approximate percentage change in the direct current (d.c.) output voltage?
- 8.Under which condition does a Zener diode maintain a nearly constant load voltage?
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