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Electrical Engineering (EE) Exam  >  Electrical Engineering (EE) Test  >  Power Electronics  >  Test: Step Down Choppers - Electrical Engineering (EE) MCQ

Step Down Choppers - Free MCQ Practice Test with solutions, GATE EE Power


MCQ Practice Test & Solutions: Test: Step Down Choppers (10 Questions)

You can prepare effectively for Electrical Engineering (EE) Power Electronics with this dedicated MCQ Practice Test (available with solutions) on the important topic of "Test: Step Down Choppers". These 10 questions have been designed by the experts with the latest curriculum of Electrical Engineering (EE) 2026, to help you master the concept.

Test Highlights:

  • - Format: Multiple Choice Questions (MCQ)
  • - Duration: 30 minutes
  • - Number of Questions: 10

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Test: Step Down Choppers - Question 1
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A buck converter has an input current of 2.4 A while required output current is 6 A. What will be the duty cycle of the converter? [Assume lossless system]

Detailed Solution: Question 1

Concept:

In a buck converter, the output voltage is given by

Vo = δVin

and Iin = δIo

Where Vo is the output voltage

Vin is the input voltage

Iin is the input current

Io is the output current

δ is the duty cycle

Calculation:

Given that, input current (Iin) = 2.4 A

Output current (Io) = 6 A

Duty cycle, 

Test: Step Down Choppers - Question 2
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Average output voltage of a step-down chopper with TON = 0.2s and TOFF = 0.3s, if the supply voltage is 15 V, is given by:

Detailed Solution: Question 2

Concept:

The average output voltage in step down chopper is given by:

where, VS = Supply voltage

Calculation:

Given, VS = 15V

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Test: Step Down Choppers - Question 3
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A buck converter is used to control a d.c. motor. The input to a dc buck converter is 200 V. Find the duty ratio of the pulse to be applied to the converter to produce 150 V across the d.c. motor.

Detailed Solution: Question 3

Concept:

In a buck converter (step down chopper)

Where,

D = Duty ratio

V0 = Average out-put voltage or DC output voltage

Vi = Input voltage

ton = On time period

T = total time period

Calculation:

V0 = 150 V, Vi = 200 V

D = 0.75 = 75%

Note:

RMS output voltage of buck converter is given by

Test: Step Down Choppers - Question 4
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A DC-DC buck converter operates in continuous conduction mode. It has 48 V input voltage, and it feeds a resistive load of 24 Ω. The switching frequency of the converter is 250 Hz. If switch-on duration is 1 ms, the load power is

Detailed Solution: Question 4

Concept:

In a buck converter (step down chopper)

Where,

D = Duty ratio

V0 = Average out-put voltage or DC output voltage

Vi = Input voltage

ton = On time period

T = total time period

I0 = output current

Calculation:

Given that, input voltage (VS) = 48 V

Resistive load (R) = 24 Ω

Switching frequency (f) = 250 Hz

Switch on duration = 1 ms

Duty cycle ratio δ = ON duration / Time period

δ = 1 / 4 = 0.25

In a buck converter,

Test: Step Down Choppers - Question 5
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The duty cycle of a step-down chopper is 55% and the value of the source voltage is 100 V. Find its output voltage.

Detailed Solution: Question 5

Step-down chopper:

It is also called a Buck converter.

The output voltage steps down compared to the input voltage.

The circuit is shown below.

Formula:

The output voltage can be calculated as

Vo = D. Vs

D = Duty cycle

Vs = Source voltage

Calculation:

Given

D = 55% = 0.55

Vs = 100 V

Vo = 0.55 × 100 = 55 V

Test: Step Down Choppers - Question 6
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A step-down chopper operates from a DC voltage source Vs and feeds a DC motor armature with counter emf Eb. From oscilloscope traces it is found that current increases for time tr, falls to zero over a time tf and remains zero for a time t0 in every chopping cycle. Then the average voltage across the motor would be

Detailed Solution: Question 6

During 0 < t < tr, the load is connected to the source and the voltage across the switch is Vs and load current increases.

During tr < t < tf, the load current decreases. This implies that the back emf is connected to the load inductance and voltage across the switch is zero as the complete back emf is dropped overload inductance.

During tf < t < t0, the load current is zero, so back emf appears across the switch.

Test: Step Down Choppers - Question 7
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For a step-down DC chopper with a resistive load, when the duty cycle is increased the average value of the output voltage-

Detailed Solution: Question 7

Concept:

So, when D increases, also increases.

 is the average load voltage.

D is the duty cycle.

 is the input voltage.

 is the voltage drop across the switch in the ON condition.

Test: Step Down Choppers - Question 8
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A step-down chopper has Vs as a source voltage, α is the duty ratio and R is the load resistance. The r.m.s. value of output voltage is

Detailed Solution: Question 8

Step-down chopper:

Case 1: When the switch is ON

The diode is reverse biased.

VO = VS

Case 2: When the switch is OFF

The diode is reverse biased.

VO = 0

The r.m.s. value of output voltage is given by:

Test: Step Down Choppers - Question 9
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A DC chopper has a resistive load of R = 10 Ω and an input voltage of Vs = 220 V. When the chopper switch remains in the ON state, its voltage drop is Vch = 2 V. If the duty cycle is 50%, determine its average output voltage Vo.

Detailed Solution: Question 9

DC chopper

It is a power electronics device that is used to convert pure DC into pulsating DC.

The average value of output voltage (pulsating value):

where, D is the duty cycle

Calculation

Source voltage (Vs) = 220 V

Vch = 2 V

When the chopper is in an ON state:

When the chopper is in an OFF state:

Vo = 0V

The waveform is given below:

The average value of output voltage is:

*Answer can only contain numeric values
Test: Step Down Choppers - Question 10
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A buck converter, as shown in Figure (a) below, is working in steady state. The output voltage and the inductor current can be assumed to be ripple free. Figure (b) shows the inductor voltage VL during a complete switching interval. Assuming all devices are ideal, the duty cycle of the buck converter is ________.


Detailed Solution: Question 10

Concept:

Buck converter: It is a switch mode DC to DC electronic converter in which the output voltage will be transformed to a level less than the input voltage. It is also called a step-down converter.

The output voltage of buck converter is given as:

Vo = D Vin

Where,

Vo is the output voltage

Vin is the input voltage

Iin is the input current

Io is the output current

D is the duty cycle

Calculation:

During ON time:

During OFF time:

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About this Electrical Engineering (EE) Practice Test

This test contains 10 MCQs on Step Down Choppers with detailed solutions for each question. It is part of the Power Electronics course on EduRev, designed to align with the current Electrical Engineering (EE) syllabus. Each solution explains not just the correct answer but also gives you an understanding of the topic — not just to attempt the question but also help you prepare for the exam with practice.

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