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September 2025 term · Electronic Systems Thinking and Circuits · EE1101

Electronic Systems Thinking and Circuits Qualifier: 26 October 2025 (September 2025 term)

The IIT Madras BS Electronic Systems Thinking and Circuits (ESTC) Qualifier paper sat on 26 Oct 2025, in the September 2025 term: 20 questions for 38 marks in 120 minutes. Every question is below with its answer. Take it as a timed mock test to be marked, or read it through first.

Questions
20
Marks
38
Duration
120 min
MCQ
14
Numerical
6
Take as mock testPractise with answers

Updated

Official paper: IIT M ES QUALIFIER AN EXAM QEQ1 26 Oct · No negative marking.

Question 1

+1 markOne correct option

The time period of any wave is generally measured as the time interval between a positive peak and the succeeding negative peak.

  1. A

    True

  2. B

    False

Show answer

Correct answer

  • B

    False

Question 1 on its own pageAlso asked in Qualifier 16 Mar 2025, Quiz 1 26 Oct 2025, Quiz 1 26 Oct 2025, Quiz 1 26 Oct 2025 and 3 more

Question 2

+1 markOne correct option
  1. A

    True

  2. B

    False

Show answer

Correct answer

  • B

    False

Question 2 on its own page

Question 3

+1 markOne correct option
  1. A

    True

  2. B

    False

Show answer

Correct answer

  • A

    True

Question 3 on its own page

Question 4

+1 markOne correct option

Voltage across an ideal inductor is zero if the current through it remains constant.

  1. A

    True

  2. B

    False

Show answer

Correct answer

  • A

    True

Question 4 on its own pageAlso asked in Quiz 1 26 Oct 2025, Quiz 1 26 Oct 2025, Quiz 1 26 Oct 2025, Quiz 1 26 Oct 2025 and 2 more

Question 5

+1 markOne correct option

For an AC signal, the RMS (root-mean-square) value is always higher than its peak value.

  1. A

    True

  2. B

    False

Show answer

Correct answer

  • B

    False

Question 5 on its own pageAlso asked in Quiz 1 26 Oct 2025, Quiz 1 26 Oct 2025, Quiz 1 26 Oct 2025, Quiz 1 26 Oct 2025 and 2 more

Question 6

+2 marksOne correct option

Which of the following circuits is not practical?

Which of the following circuits is not practical?

  1. A

    Both II and III

  2. B

    Both I and II

  3. C

    I

  4. D

    I, II, and IV

Show answer

Correct answer

  • C

    I

Question 6 on its own page

Question 7

+2 marksOne correct option
  1. A

    1

  2. B

    -1

  3. C

    2

  4. D

    -2

Show answer

Correct answer

  • B

    -1

Question 7 on its own page

Question 8

+2 marksOne correct option
  1. A

    20

  2. B

    18

  3. C

    8

  4. D

    10

Show answer

Correct answer

  • C

    8

Question 8 on its own page

Question 9

+2 marksOne correct option
  1. A

    0

  2. B

    2

  3. C

    3

  4. D

    4

Show answer

Correct answer

  • A

    0

Question 9 on its own page

Question 10

+2 marksOne correct option

The value of the voltage source V3 (in V) is ______ V.

The value of the voltage source V3 (in V) is ______ V.

  1. A

    -16

  2. B

    4

  3. C

    -6

  4. D

    16

Show answer

Correct answer

  • A

    -16

Question 10 on its own page

Question 11

+2 marksOne correct option
  1. A

    0

  2. B

    5

  3. C

    2

  4. D

    1

Show answer

Correct answer

  • A

    0

Question 11 on its own page

Question 12

+2 marksOne correct option

In a household, the following electrical appliances are used every day:
• 4 bulbs, each rated at 30 W, operated for 5 hours • 4 tube lights, each rated at 50 W, operated for 8 hours • 1 air conditioner rated at 1000 W, operated for 1 hour
Assume each appliance draws power continuously whenever it is switched ON. If 1 unit of electrical energy = 1 kWh, determine the total number of units of electrical energy consumed in a 30-day month.

  1. A

    91.5

  2. B

    96

  3. C

    92.5

  4. D

    95

Show answer

Correct answer

  • B

    96

Question 12 on its own pageAlso asked in Quiz 1 26 Oct 2025, Quiz 1 26 Oct 2025, Quiz 1 26 Oct 2025, Quiz 1 26 Oct 2025 and 2 more

Question 13

+2 marksOne correct option
  1. A

    15

  2. B

    45

  3. C

    55

  4. D

    30

Show answer

Correct answer

  • D

    30

Question 13 on its own page

Question 14

+2 marksOne correct option

An ideal 1800 mAh battery is powering a load that draws a constant current of 60 mA. How long will the fully charged battery last before it drains completely?

  1. A

    10 hours

  2. B

    15 hours

  3. C

    40 hours

  4. D

    30 hours

Show answer

Correct answer

  • D

    30 hours

Question 14 on its own pageAlso asked in Quiz 1 26 Oct 2025, Quiz 1 26 Oct 2025, Quiz 1 26 Oct 2025, Quiz 1 26 Oct 2025 and 2 more

Question 15

+2.5 marksNumerical answer

The figure shows a sinusoidal waveform. With reference to the graph shown below, answer the given subquestions.

The figure shows a sinusoidal waveform. With reference to the graph shown below, answer the given subquestions.

The RMS (Root Mean Square) value (in V) of the waveform is ______V.

Show answer

Correct answer: 1.435 (accepted within ±0.075)

Question 15 on its own page

Question 16

+2.5 marksNumerical answer

The figure shows a sinusoidal waveform. With reference to the graph shown below, answer the given subquestions.

The figure shows a sinusoidal waveform. With reference to the graph shown below, answer the given subquestions.

If the fundamental frequency of the waveform is obtained from the plot, then the frequency of its fourth harmonic is ______ Hz.

Show answer

Correct answer: 160

Question 16 on its own page

Question 17

+2.5 marksNumerical answer

Consider the circuit given below.

Consider the circuit given below.
Based on the above data, answer the given subquestions.

Find the equivalent capacitance (in μF) across the terminals A and B.

Show answer

Correct answer: 15

Question 17 on its own page

Question 18

+2.5 marksNumerical answer

Consider the circuit given below.

Consider the circuit given below.
Based on the above data, answer the given subquestions.

Now, if a 20 V voltage source is connected across A and B, find the voltage (in V) across the 30 μF capacitor, V1 in _______V.

Now, if a 20 V voltage source is connected across A and B, find the voltage (in V) across the 30 μF capacitor, V1 in _______V.

Show answer

Correct answer: 10

Question 18 on its own page

Question 19

+2.5 marksNumerical answer

Consider the circuit given below.

Consider the circuit given below.
Based on the above data, answer the given subquestions.

Now, if a 20 V voltage source is connected across A and B, find the voltage (in V) across the 20 μF capacitor, V3 in __________V.

Now, if a 20 V voltage source is connected across A and B, find the voltage (in V) across the 20 μF capacitor, V3 in __________V.

Show answer

Correct answer: 10

Question 19 on its own page

Question 20

+2.5 marksNumerical answer

Consider the circuit given below.

Consider the circuit given below.
Based on the above data, answer the given subquestions.

Now, if a 20 V voltage source is connected across A and B, find the charge (in μC) stored on the 20 μF capacitor is ________μC.

Now, if a 20 V voltage source is connected across A and B, find the charge (in μC) stored on the 20 μF capacitor is ________μC.

Show answer

Correct answer: 200

Question 20 on its own page