Sinusoidal Steady State Analysis MCQ Quiz - Objective Question with Answer for Sinusoidal Steady State Analysis - Download Free PDF

Last updated on May 14, 2025

Latest Sinusoidal Steady State Analysis MCQ Objective Questions

Sinusoidal Steady State Analysis Question 1:

Current I(s) in RL circuit is given as \(\rm I(s)=\frac{1.5}{s+4}\) Obtain i(t) for t > 0

  1. 1.5 e4t
  2. 1.5 e-4t
  3. 1.5 t
  4. 1.5 et

Answer (Detailed Solution Below)

Option 2 : 1.5 e-4t

Sinusoidal Steady State Analysis Question 1 Detailed Solution

Concept

The inverse Laplace Transform of 

\({k\over s+a}=ke^{-at}\)

where, k = Constant

Calculation

Given, \(\rm I(s)=\frac{1.5}{s+4}\)

On comparison, k = 1.5 and a = 4

\({1.5\over s+4}=1.5e^{-4t}\)

Sinusoidal Steady State Analysis Question 2:

If the peak voltage of a full-wave rectifier is 20 V, what is the average output voltage?

  1. \(\frac{\pi}{20}V\)
  2. \(\frac{\pi}{40}V\)
  3. \(\frac{20}{\pi}V\)
  4. \(\frac{40}{\pi}V\)

Answer (Detailed Solution Below)

Option 4 : \(\frac{40}{\pi}V\)

Sinusoidal Steady State Analysis Question 2 Detailed Solution

Concept

The average and RMS value of the full and half-wave rectifier are given by:

Full wave rectifier:

\(V_{o(avg)}={2V_m\over \pi}\)

\(V_{o(rms)}={V_m\over \sqrt{2}}\)

Half-wave rectifier:

\(V_{o(avg)}={V_m\over \pi}\)

\(V_{o(rms)}={V_m\over 2}\)

Calculation

Given, Vm = 20V

The average output voltage is given by:

\(V_{o(avg)}={2\times 20\over \pi}\)

\(V_{o(avg)}=\frac{40}{\pi}V\)

Sinusoidal Steady State Analysis Question 3:

What will be the current relationship in time domain for a capacitive circuit?

  1. \(\rm C\frac{d^2v}{dt^2}\)
  2. \(\rm i(t)=C\frac{dv}{dt}\)
  3. \(\rm i(t)=C\int_0^tv(t)\)
  4. \(\rm i(t)=C\int_0^tv(t)+i(0)\)

Answer (Detailed Solution Below)

Option 2 : \(\rm i(t)=C\frac{dv}{dt}\)

Sinusoidal Steady State Analysis Question 3 Detailed Solution

Concept

The current through a capacitor is given by:

\(I_C=C{dV_C\over dt}\)

where, \({dV_C\over dt}=\) Rate of change of capacitor voltage

The voltage across a capacitor is given by:

\(V_c(t)={1\over C } \int I_c(t) dt\)

Sinusoidal Steady State Analysis Question 4:

What will be the voltage relationship of frequency domain relation for inductor having time domain v(t) = Ldi/dt?

  1. V(s) = LsI(s) − Li(0)
  2. V(s) = LI(s)
  3. V(s) = LsI(s)
  4. V(s) = LI(s) − Li(0)

Answer (Detailed Solution Below)

Option 1 : V(s) = LsI(s) − Li(0)

Sinusoidal Steady State Analysis Question 4 Detailed Solution

Concept

When an inductor is represented in the frequency domain, it is represented as sL and the initial current across the inductor is also considered.

qImage6812163c91ab4414ddec3333

After source transformation:

qImage6812163c91ab4414ddec3335

V(s) = sL × I(s) − Li(0)

Sinusoidal Steady State Analysis Question 5:

If the power factor of a three-phase system is 0.8, and the apparent power is 10 kVA, then what is the active power?

  1. 8 kW
  2. 10 kW
  3. 12 kW
  4. 6 kW

Answer (Detailed Solution Below)

Option 1 : 8 kW

Sinusoidal Steady State Analysis Question 5 Detailed Solution

Power Triangle

F1 Vinanti Engineering 22.03.23 D5

In the given figure, the given terms represent the type of power:

P = Active Power

Q = Reactive Power 

S = Apparent Power

The power factor is given by:

\(cosϕ={P\over S}\)

Calculation

Given, cos ϕ = 0.8

S = 10 kVA

The active power is given by:

\(0.8={P\over 10}\)

P = 8 kW

Top Sinusoidal Steady State Analysis MCQ Objective Questions

Two circuits having the same magnitudes of impedances are joined in parallel. The power factor of one circuit is 0.8 and of other is 0.6. The power factor of the combination is -

  1. 0.6
  2. 0.75
  3. 0.7071
  4. 0.8

Answer (Detailed Solution Below)

Option 3 : 0.7071

Sinusoidal Steady State Analysis Question 6 Detailed Solution

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Calculation,

Given,

cos ϕ1 = 0.8

∴ sin ϕ1 = 0.6

cos ϕ2 = 0.6

∴ sin ϕ2 = 0.8

Asuume,

|I1| = |I2| = |I|

In complex form the phasor quantity is written as,

i = I(cos ϕ ± jsin ϕ)

Both current can be written as,

i1 = |I|(0.8 + j0.6)

i2 = |I|(0.6 + j0.8)

Resultant current (i) will be phasor sum of i1 and i2,

i = |I|(0.8 + j0.6) + |I|(0.6 + j0.8) = |I|(1.4 + j1.4)

Phase angle can caculated as,

\(\tan ϕ = \frac{imaginarry\ component}{real\ component }=\frac{1.4}{1.4 } = 1\)

ϕ = tan-1 (1) = 45° 

Hence,

Power factor = cos 45° = 0.707

Alternate Method

When two circuits having the same magnitudes of impedances are joined in parallel. The power factor of the combination is 

\(\cos ϕ = \frac{1}{{\sqrt {1 + \left( {{{\cos }^2}{ϕ _1} + {{\cos }^2}{ϕ _2}} \right)} }}\)

The power factor of the first circuit = 0.8 (cos ϕ1)

Power factor of second circuit = 0.6 (cos ϕ2)

The power factor of parallel combination,

\(\cos ϕ = \frac{1}{{\sqrt {1 + \left( {{{\cos }^2}{ϕ _1} + {{\cos }^2}{ϕ _2}} \right)} }}\)

\(= \frac{1}{{\sqrt {1 + {{\left( {0.8} \right)}^2} + {{\left( {0.6} \right)}^2}} }} = \frac{1}{{\sqrt 2 }} = 0.707\)

Three currents i1, i2, and i3 meet at a node. if i1 = 10 sin (400t + 60°) A, and i2 = 10sin (400t - 60°) A then i3 =

  1. 0
  2. 10sin 400t A
  3. -10sin 400t A
  4. -5 √3 sin 400t

Answer (Detailed Solution Below)

Option 3 : -10sin 400t A

Sinusoidal Steady State Analysis Question 7 Detailed Solution

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Kirchhoff’s Current Law (KCL): It states that the algebraic sum of currents entering a node or closed boundary is zero.

Mathematically, KCL implies that

\(\mathop \sum \limits_{n = 1}^N {i_n} = 0 \)

Where N is the number of branches connected to the node

And in is the nth current entering or leaving the node.

By this law current entering a node may be regarded as positive and current leaving a node may be regarded as negative or vice-versa.

Hence, the sum of currents entering a node is equal to the sum of the currents leaving the node.

Calculation:

Given that, three currents i1, i2, and i3 meet at a node,

From the above concept,

i1,+ i2, + i3 = 0

or,  i3 = - (i+ i2)

Since the current is given in phasor form, hence the addition of current i1 and i2 can be done by using the parallelogram method,

We have,

i1 = 10 sin (400t + 60°) A .... (1)

i2 = 10sin (400t - 60°) A .... (2)

The phasor diagram can be drawn as,

F1 Nakshatra  23-09-21 Savita D2

By using the parallelogram method,

 |ir| = \(\sqrt{i_1^2+i^2_2+2i_1i_2cosθ}\) .... (3)

Where, it is the resultant current

We have, θ = (60° + 60°) = 120°

From equation (1), (2) & (3),

|ir| = \(\sqrt{10^2+10^2+200cos120 ^\circ}\)

|ir| = \(\sqrt{10^2+10^2+200\times -0.5}=10\)

Since i1 & i2 has the same phase angle as well as the magnitude,

∴ ir = 10sin 400t A

Since the sum of all current is zero, hence,

i3 = - ir = - 10sin 400t A

The impedance of a circuit is given by Z = 3 + j4. Its conductance will be:

  1. \(\frac{3}{7}\)
  2. \(\frac{3}{{25}}\)
  3. \(\frac{3}{4}\)
  4. \(\frac{1}{3}\)

Answer (Detailed Solution Below)

Option 2 : \(\frac{3}{{25}}\)

Sinusoidal Steady State Analysis Question 8 Detailed Solution

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Concept:

The impedance(Z) of a circuit can be written as:

Z = R ± jX

R = Resistance

X = Reactance

The admittance(Y) can be written as:

Y = G ± jB   ---(1)

G = Conductance

B = Susceptance

\(Y = \frac{1}{Z}\)

Calculation:

Z = 3 + j4

\(Y = \frac{1}{Z} = \frac{1}{{3 + j4}} \)

\(= \frac{{\left( {3 - j4} \right)}}{{\left( {3 + j4} \right)\left( {3 - j4} \right)}} \)

\(Y= \frac{3}{{25}} - \frac{{j4}}{{25}}\)

Comparing this with Equation (1), we get:

\(G= \frac{3}{{25}}\)

Mistake Point:

The conductance will not be 1/R. For a given impedance, the conductance will be:

\(G=\frac{R}{|Z|^2}\)

R = Resistance 

|Z|2 = Square of the magnitude of impedance

Select the option that will give the average value of the following waveform:

F1 Uday 18-9-2020 Swati D5

  1. \(\frac{{\pi - 2\alpha }}{\pi }{F_m}\)
  2. \(\frac{{\pi + \alpha }}{\pi }{F_m}\)
  3. Fm / π
  4. \(\frac{{\pi - \alpha }}{\pi }{F_m}\)

Answer (Detailed Solution Below)

Option 4 : \(\frac{{\pi - \alpha }}{\pi }{F_m}\)

Sinusoidal Steady State Analysis Question 9 Detailed Solution

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Concept:

The average value of a periodic waveform is given as

\({F_{avg}} = \frac{1}{T}\mathop \smallint \limits_0^T f\left( t \right)dt\)

It is also calculated by calculating the area of the given waveform.

\({F_{avg}} = \frac{A}{T}\)

Where A is the area

RMS value of a periodic waveform is given as

\({F_{rms}} = \sqrt {\frac{1}{T}\mathop \smallint \limits_0^T {{\left[ {f\left( t \right)} \right]}^2}dt} \)

Where T is the time-period of the given waveform.

Calculation:

F1 Uday 18-9-2020 Swati D5

Time period of the given waveform (T) = π

The area of the given waveform is,

\(A = \left( {\frac{1}{2} \times \alpha \times {F_m}} \right) + {F_m}\left( {\pi - 2\alpha } \right) + \left( {\frac{1}{2} \times \alpha \times {F_m}} \right)\)

= Fm (π – α)

Average value \( = \frac{{\pi - \alpha }}{\pi }{F_m}\)

The current in a circuit follows the relation i = 200 sin ωt. If frequency is 50 Hz, how long will it take for the current to rise to 100 A?

  1. 3.33 ms
  2. 5.98 ms
  3. 0.32 ms
  4. 1.66 ms

Answer (Detailed Solution Below)

Option 4 : 1.66 ms

Sinusoidal Steady State Analysis Question 10 Detailed Solution

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Concept:

Equation of current is I = Im sin ωt

Im = Maximum current

ω = Angular frequency = 2πf

f = Frequency

Calculation:

Given, I = 100 A

f = 50 Hz

100 = 200 sin 2 × π × 50 × t

100 × π × t = 30° = π/6

t = 1/600 s   

t = 1.666 ms

In the waveform shown, RMS value of voltage is

F1 J.P 12.5.20 Pallavi D1

  1. \(\frac{{{200}}}{\pi }\)
  2. \(\frac{{{100}}}{\pi }\)
  3. 200 V
  4. 100 V

Answer (Detailed Solution Below)

Option 4 : 100 V

Sinusoidal Steady State Analysis Question 11 Detailed Solution

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Concept:

RMS (Root mean square) value:

  • RMS value is based on the heating effect of wave-forms.
  • The value at which the heat dissipated in AC circuit is the same as the heat dissipated in DC circuit is called RMS value provided, both the AC and DC circuits have equal value of resistance and are operated at the same time.
  • RMS value 'or' the effective value of an alternating quantity is calculated as:

    \({V_{rms}} = \sqrt{\frac{1}{T}\mathop \smallint \limits_0^T {v^2}\left( t \right)dt} \)

    T = Time period

Note:

  • Average or mean value of alternating current is that value of steady current which sends the same amount of charge through the circuit in a certain interval of time as is sent by alternating current through the same circuit in the same interval of time
  • The ratio of the maximum value (peak value) to RMS value is known as the peak factor or crest factor.
  • \(Peak\;factor = \frac{{maximum\;value}}{{rms\;value}}\)
  • The ratio of RMS value to the average value is known as the form factor.
  • \(Form\;factor = \frac{{rms\;value}}{{average\;value}}\)

Calculation:

For a rectangular wave, the RMS value is equal to the average value. RMS value is also equal to peak value.

For given waveform RMS value is 100 V.

IMPORTANT EVALUATIONS:

WAVEFORM

MAX.

VALUE

AVERAGE VALUE

RMS VALUE

FORM FACTOR

CREST FACTOR

SINUSOIDAL WAVE

\({A_m}\)

\(\frac{{2{A_m}}}{\pi }\)

\(\frac{{{A_m}}}{{\sqrt 2 }}\)

\(\frac{{\frac{{{A_m}}}{{\sqrt 2 }}}}{{\frac{{2{A_m}}}{\pi }}} = 1.11\)

\(\frac{{{A_m}}}{{\frac{{{A_m}}}{{\sqrt 2 }}}} = \sqrt 2 \)

SQUARE WAVE

\({A_m}\)

 

\({A_m}\)

 

 

\({A_m}\)

 

\(\frac{{{A_m}}}{{{A_m}}} = 1\)

\(\frac{{{A_m}}}{{{A_m}}} = 1\)

TRIANGULAR WAVE

\({A_m}\)

\(\frac{{{A_m}}}{2}\)

\(\frac{{{A_m}}}{{\sqrt 3 }}\)

\(\frac{{\frac{{{A_m}}}{{\sqrt 3 }}}}{{\frac{{{A_m}}}{2}}} = \frac{2}{{\sqrt 3 }}\)

\(\frac{{{A_m}}}{{\frac{{{A_m}}}{{\sqrt 3 }}}} = \sqrt 3 \)

HALF-WAVE RECTIFIED WAVE

 

\({A_m}\)

\(\frac{{{A_m}}}{\pi }\)

\(\frac{{{A_m}}}{2}\)

\(\frac{{\frac{{{A_m}}}{2}}}{{\frac{{{A_m}}}{\pi }}} = \frac{\pi }{2}\)

\(2\)

The voltage transfer function of the network shown in the figure below is

F2 Madhuri Engineering 20.05.2022 D2

  1. \(\frac{1}{{1 + 2s}}\)
  2. 1 + 4s
  3. 6 - s
  4. \(\frac{1}{{1 + 2{s^2}}}\)

Answer (Detailed Solution Below)

Option 4 : \(\frac{1}{{1 + 2{s^2}}}\)

Sinusoidal Steady State Analysis Question 12 Detailed Solution

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Concept:

The Laplace transform resistance, inductor, and capacitance are given by:

  1. Resistance: R
  2. Inductor: sL
  3. Capacitor: \({1\over sC}\)

​Calculation:

The circuit diagram in the Laplace domain is given below:

F2 Madhuri Engineering 20.05.2022 D3

Applying voltage division rule across capacitor:

\(V_{out}(s) = V_{in}\times{{1 \over s}\over {1 \over s}+2s}\)

\({V_{out}(s)\over V_{in}(s)} ={1\over{1 +2s^2}}\)

Currents through ammeters A2 and A3 in the figure are 1∠10° and 1∠70°, respectively. The reading of the ammeter A1 (rounded off to 3 decimal places) is _____ A.

F2 U.B Madhu 24.04.20 D 8

Answer (Detailed Solution Below) 1.700 - 1.750

Sinusoidal Steady State Analysis Question 13 Detailed Solution

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Concept:

KCL in DC circuits:

According to Kirchhoff’s current law (KCL), the algebraic sum of the electric currents meeting at a common point is zero. I.e. the sum of currents entering a node is equal to the sum of currents leaving the node. It is based on the conservation of charge.

KCL in AC circuits:

Kirchhoff’s current law as applied to the ac circuit is defined as the phasor sum of currents entering the node is equal to the phasor sum of currents leaving the node.

Calculation:

By applying KCL at the node,

I1 = I2 + I3

I1 = 1∠10° + 1∠70°

= (cos 10 + j sin 10) + (cos 70 + j sin 70)

= (cos 10 + cos 70) + j(sin 10 + sin 70)

= 1.3268 + j1.1133 A

I1 = 1.732 40° A

A 120 Ω resistor is in parallel with a capacitor with a capacitive reactance of 40Ω. Both components are across a 20 V AC source. What is the magnitude of the total current through the circuit?

  1. \(\sqrt {\frac{1}{{120}}} A\)
  2. \(\sqrt {\frac{2}{{9}}} A\)
  3. \(\sqrt {\frac{1}{{40}}} A\)
  4. \(\sqrt {\frac{5}{{18}}} A\)

Answer (Detailed Solution Below)

Option 4 : \(\sqrt {\frac{5}{{18}}} A\)

Sinusoidal Steady State Analysis Question 14 Detailed Solution

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The correct answer is option 4):\(\sqrt {\frac{5}{{18}}} A\)

Concept:

The magnitude of the total current through the circuit

I = \(\sqrt{I_R^2+(I_L -I_C)^2} \)

where

IR is the resistive component of current

IL  is the Inductive component of current

IC  is the Capacitive component of current

IR = \(V\over R\)

V is the voltage

R is the resistance

IC = \(V\over X_c\)

Xc is the capacitive reactance

IL = \(V\over X_L\)

X is the inductive reactance

Calculation:

The impedance of a network is given as

I = \(\sqrt{I_R^2+(I_L -I_C)^2} \)

IR \(20 \over 120 \)

\(1\over 6\)

Ic = \(20 \over 40\)

\(1\over 2\)

I = \(\sqrt(\frac{1}{36}+\frac{1}{4})\)

\(\sqrt {{4+36} \over 36\times 4}\)

=\( \sqrt{10 \over 36} \)

\(\sqrt {\frac{5}{{18}}} A\)

A series Circuit Containing a circuit element has following current and applied voltage

V = 200 Sin (2000t + 50°) V

i = 4 cos (2000t + 13.2°) A

The element Comprising the circuit is

  1. A pure inductor
  2. A pure capacitor
  3. A practical capacitor
  4. A practical inductor

Answer (Detailed Solution Below)

Option 3 : A practical capacitor

Sinusoidal Steady State Analysis Question 15 Detailed Solution

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Given that,

V = 200 Sin (2000t + 50°) V

i = 4 cos (2000t + 13.2°) A

We know that,

sin (90 + ϕ) = cos ϕ 

⇒ V = 200 sin (2000t + 50°) V  --------- (i)

⇒ i = 4 sin (2000t + 13.2°+ 90°) A

⇒ i = 4 sin (2000t + 103.2°) A    ------- (ii)

From, (i) and (ii) we can observe that,

Current 'i' is leading voltage V by 53.2° 

Hence, the element is practical capacitor

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