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MCQOPTIONS
This section includes 785 Mcqs, each offering curated multiple-choice questions to sharpen your Electronic Devices Circuits knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
In the first Cauer LC network, the first element is a series inductor when the driving point function consists of a |
| A. | Pole at ω = ∞ |
| B. | Zero at ω = ∞ |
| C. | Pole at ω = 0 |
| D. | Zero at ω = 0 |
| Answer» B. Zero at ω = ∞ | |
| 102. |
Find the RMS value of the given current waveform. |
| A. | I = 12.5 A |
| B. | \(I=\frac{50}{\sqrt 3}\)A |
| C. | I = 25 A |
| D. | \(I=\frac{25}{\sqrt 2}\)A |
| Answer» C. I = 25 A | |
| 103. |
For a pure sinusoidal waveform the form factor and crest factor are______ and ______ respectively. |
| A. | 1.414, 1.11 |
| B. | 1.11, 1.414 |
| C. | 11.1, 14.14 |
| D. | 14.14, 11.1 |
| Answer» C. 11.1, 14.14 | |
| 104. |
A capacitor acts as an infinite resistance for ___________ . |
| A. | AC |
| B. | DC as well as AC |
| C. | either AC nor DC |
| D. | DC |
| Answer» E. | |
| 105. |
An alternating voltage has a frequency of 50 Hz, peak amplitude of 200 V, and value at t = 0 of 100 V. what is the equation of voltage? |
| A. | v = 200 sin 314 t |
| B. | v = 200 sin (314 t + 30° ) |
| C. | v = 100 sin (314t + 60° ) |
| D. | v = 200 sin (377 t + 30° ) |
| Answer» C. v = 100 sin (314t + 60° ) | |
| 106. |
An electrical system transfer function has a pole at s = - 2 and a zero at s = -1 with a system gain of 10. For sinusoidal current excitation, voltage response of the system. |
| A. | Is zero |
| B. | Is in phase with the current |
| C. | Leads the current |
| D. | Lags behind the current |
| Answer» D. Lags behind the current | |
| 107. |
Power factor of an AC circuit is equal to |
| A. | \(\frac{R}{X_C}\) |
| B. | \(\frac{R}{X_L}\) |
| C. | \(\frac{R}{Z}\) |
| D. | \(\frac{Z}{R}\) |
| Answer» D. \(\frac{Z}{R}\) | |
| 108. |
An average reading digital multimeter reads 10 V when fed with a triangular wave, symmetric above the time axis. For the same input a rms, reading will read |
| A. | 20/3 |
| B. | 10/√3 |
| C. | 20/√3 |
| D. | None of the above |
| Answer» D. None of the above | |
| 109. |
A 120 V, 20 Hz source supplies a series circuit consisting of a 5 Ω capacitive reactance, a 1.6 Ω resistor, and a coil with resistance and inductive reactance of 3 Ω and 1.2 Ω respectively.(i) The input impedance is Z(ii) The circuit current is I(iii) The voltage across the coil is VL(iv) The resonant frequency frArrange the above in increasing order of their numerical values. |
| A. | (i), (ii), (iv), (iii) |
| B. | (iv), (iii), (ii), (i) |
| C. | (iv), (i), (ii), (iii) |
| D. | (iv), (ii), (iii), (i) |
| Answer» B. (iv), (iii), (ii), (i) | |
| 110. |
In case of a purely inductive circuit, the current is maximum when: |
| A. | The applied voltage is maximum |
| B. | The applied voltage is half of the maximum |
| C. | The applied voltage is zero |
| D. | The applied voltage is negative maximum |
| Answer» D. The applied voltage is negative maximum | |
| 111. |
A resistance R Ω and inductance of L H are connected in series across 240 V, 50 Hz supply. Power dissipated in the circuit is 300 W and the voltage across R is 100 V. In order to improve the power factor to unity, the capacitor that is to be connected in series should have a value of: |
| A. | 43.7 μF |
| B. | 4.37 μF |
| C. | 437 μF |
| D. | 0.437 μF |
| Answer» B. 4.37 μF | |
| 112. |
In an A.C. capacitive circuit the current ______ voltage by ________ degrees |
| A. | lags, 90 |
| B. | leads, 90 |
| C. | lags, 0 |
| D. | lags, 30 |
| Answer» C. lags, 0 | |
| 113. |
A series RL circuit has a resistance of 5 kΩ and inductive reactance of 5 kΩ. What is the magnitude and phase angle of the effective impedance? |
| A. | 7.07 kΩ, 45° |
| B. | 5 kΩ, 45° |
| C. | 7.07 kΩ, 90° |
| D. | 5 kΩ, 90° |
| Answer» B. 5 kΩ, 45° | |
| 114. |
By improving the power factor of the system, the kW h delivered by the generating station: |
| A. | decreases |
| B. | does not change |
| C. | increases |
| D. | becomes zero |
| Answer» D. becomes zero | |
| 115. |
Calculate the time (in seconds) taken by the capacitor of a series RC circuit having a capacitance of 0.01 mF and resistance of 300 Ohms, to get fully charged. |
| A. | 0.007 |
| B. | 0.015 |
| C. | 0.15 |
| D. | 0.3 |
| Answer» C. 0.15 | |
| 116. |
How the inductive reactance changes as the frequency of AC voltage applied across the inductive load increases? |
| A. | Increases linearly |
| B. | Decreases linearly |
| C. | Remains the same |
| D. | Increases proportional to the square of the frequency |
| Answer» B. Decreases linearly | |
| 117. |
In a series RL circuit, the current i(t) = 5 cos (628t + 2π/3) and the voltage v(t) = 20 cos (628 t + 5π/6), find power factor and average power drawn by the circuit? |
| A. | 0.866 (lagging), 43.3 W |
| B. | 0.866 (leading), 43.3 W |
| C. | 0.866 (leading), 100 W |
| D. | 0.866 (lagging), 50 W |
| Answer» B. 0.866 (leading), 43.3 W | |
| 118. |
A mathematical expression for 50 Hz sinusoidal voltage of peak value 80 V will be |
| A. | v = 50 sin 314 t |
| B. | v = 50 sin 80 t |
| C. | v = 80 sin 314 t |
| D. | v = 80 sin 50 t |
| Answer» D. v = 80 sin 50 t | |
| 119. |
. A two-branch parallel circuit with 100 Ω resistor in one branch and a single unknown element in the other branch has the following applied voltage and total current.Voltage: 2000 cos (1000t + 45°) V, Total current: 45 sin (1000t + 135°) A.Find the unknown element |
| A. | Resistor |
| B. | Capacitor |
| C. | Inductor |
| D. | None of these |
| Answer» B. Capacitor | |
| 120. |
In an a.c. circuit, \(v = 50\sin \left( {\omega t + 60^\circ } \right),\;i = 10{\rm{cos}}\left( {\omega t} \right)\) then the power factor of a.c. circuit will be: |
| A. | 0.5 lag |
| B. | 0.5 lead |
| C. | 0.866 lag |
| D. | 0.866 lead |
| Answer» E. | |
| 121. |
A voltage of 100 V is applied to an impedance of Z = (3 + j4) Ω. What are the values of active power, reactive power and volt-amperes respectively? |
| A. | 1200 W, 1200 VAR and 2200 VA |
| B. | 1600 W, 1600 VAR and 2200 VA |
| C. | 1200 W, 1600 VAR and 2000 VA |
| D. | 1600 W, 1200 VAR and 2200 VA |
| Answer» D. 1600 W, 1200 VAR and 2200 VA | |
| 122. |
A source Vs = 200 cos ωt delivers power to a load at power factor 0.8 lag. The reactive power is 300 VAR. The Active Power is given by? |
| A. | 200 Watts |
| B. | 225 Watts |
| C. | 400 watts |
| D. | 300 Watts |
| Answer» D. 300 Watts | |
| 123. |
If V1 is the fundamental voltage, V3 and V5 are the amplitudes of the 3rd and 5th harmonic and \(\frac{{{V_3}}}{{{V_1}}} = x\% ,\;\frac{{{V_5}}}{{{V_1}}} = y\% \) then the total harmonic distortion of the system will be |
| A. | \(\sqrt {{x^2} + {y^2}} \) |
| B. | \(\frac{y}{x}\) |
| C. | x + y |
| D. | \(\frac{1}{{\sqrt {{x^2} + {y^2}} }}\) |
| Answer» B. \(\frac{y}{x}\) | |
| 124. |
KVAR power is equal to: |
| A. | KVA cosϕ |
| B. | KVA sinϕ |
| C. | KW cosϕ |
| D. | KW sinϕ |
| Answer» C. KW cosϕ | |
| 125. |
In a series RC circuit, the current ____ the voltage by an angle ____ degrees. |
| A. | lags, of 45° |
| B. | lags, of 0° |
| C. | leads, between 0° and 90° |
| D. | leads, of 90° |
| Answer» D. leads, of 90° | |
| 126. |
Find the transfer function \(\frac{{{V_c}\left( s \right)}}{{V\left( s \right)}}\) for the circuit: |
| A. | \(\frac{R}{{LC{s^2} + RCs + 1}}\) |
| B. | \(\frac{1}{{LC{s^2} + RCs + 1}}\) |
| C. | \(\frac{{LC}}{{LC\;{s^2} + RCs + 1}}\) |
| D. | \(\frac{C}{{LC{s^2} + RC\;s + 1}}\) |
| Answer» C. \(\frac{{LC}}{{LC\;{s^2} + RCs + 1}}\) | |
| 127. |
In an inductive circuit, if the active and reactive components of line current are equal, then its power factor is: |
| A. | 0.707 lagging |
| B. | 0.5 lagging |
| C. | 0.707 leading |
| D. | zero |
| Answer» B. 0.5 lagging | |
| 128. |
Consider a capacitor and resistor connected in series to a sinusoidal voltage source. The voltage across the capacitor lags the voltage across the resistor by an angle θ degrees. What is the value of θ? |
| A. | 90 |
| B. | -90 |
| C. | 180 |
| D. | -180 |
| Answer» B. -90 | |
| 129. |
A 15 V AC source is applied to a load impedance of (3 – j4) Ω. Find the load current. |
| A. | (1.8 – j2.4) A |
| B. | (1.8 + j2.4) A |
| C. | (2.4 + j1.8) A |
| D. | (2.4 – j1.8) A |
| Answer» C. (2.4 + j1.8) A | |
| 130. |
For a full wave rectifier, if the peak voltage applied is 3.14 V, then the average value of the voltage at the output is: |
| A. | 1 V |
| B. | 0.5 V |
| C. | 2 V |
| D. | 0.25 V |
| Answer» D. 0.25 V | |
| 131. |
A sinusoidal voltage V = 50 sin ωt is applied to a series RL circuit. The current in the circuit is given by I = 25 sin (ωt – 53°). The apparent power consumed by the load is |
| A. | 375 VA |
| B. | 625 VA |
| C. | 2500 VA |
| D. | 750 VA |
| Answer» C. 2500 VA | |
| 132. |
If Vm is the maximum voltage, then the average voltage of the waveform will be given by: |
| A. | Vm / 2 |
| B. | 2Vm / π |
| C. | Vm / π |
| D. | Vm / 2π |
| Answer» D. Vm / 2π | |
| 133. |
A 2-pole, 50 Hz, 11 kV turbo-generator has a rating of 60 MW, lagging power factor 0.8. What would be the rating of the machine in MVA? |
| A. | 85 MVA |
| B. | 55 MVA |
| C. | 75 MVA |
| D. | 65 MVA |
| Answer» D. 65 MVA | |
| 134. |
If the voltage and current in an AC circuit are represented as \(v = 240\sin \left( {314t - \frac{\pi }{6}} \right)\) and \(i = 40\sin \left( {314t + \frac{\pi }{3}} \right)\), then the power factor of the circuit is: |
| A. | 30° leading |
| B. | Unity |
| C. | Zero lagging |
| D. | Zero leading |
| Answer» E. | |
| 135. |
In the figure, the voltages are v1(t) = 100 cos (ωt), v2(t) = 100 cos (ωt + π/18) and v3(t) = 100 cos (ωt + π/36). The circuit is in sinusoidal steady state, and R << ωL. P1, P2 and P3 are the average power outputs. Which one of the following statements is true? |
| A. | P1 = P2 = P3 = 0 |
| B. | P1 < 0, P2 > 0, P3 > 0 |
| C. | P1 < 0, P2 > 0, P3 < 0 |
| D. | P1 > 0, P2 < 0, P3 > 0 |
| Answer» D. P1 > 0, P2 < 0, P3 > 0 | |
| 136. |
A unit step voltage 2u(t - θ) is applied in a series RC circuit with R = 2Ω, C = 1F. Assuming zero initial conditions, find i(t) |
| A. | i(t) = u(t) e0.5(t) A |
| B. | i(t) = u(t - 2θ) e-0.5(t-2θ) A |
| C. | i(t) = u(t - θ) e-0.5(t-θ) A |
| D. | i(t) = u(t - θ ) e- (t- θ) A |
| Answer» D. i(t) = u(t - θ ) e- (t- θ) A | |
| 137. |
For an RL circuit, the power factor cannot be less than_____ or greater than _____ |
| A. | 0, 1 |
| B. | -1, 0 |
| C. | -1, 1 |
| D. | 1, 0 |
| Answer» B. -1, 0 | |
| 138. |
An amplifier operating from a single +15 V supply provides a 6 V peak sine wave signal to 1 KΩ load. DC current drawn from the supply is 8 mA. What is the power dissipation in the amplifier? |
| A. | 120 mW |
| B. | 18 mW |
| C. | 102 mW |
| D. | 225 mW |
| Answer» D. 225 mW | |
| 139. |
For RMS 100 value triangular wave, the peak voltage will be: |
| A. | 173 V |
| B. | 141 V |
| C. | 111 V |
| D. | 100 V |
| Answer» B. 141 V | |
| 140. |
Calculate the full-load voltage given that the power supply has 5% voltage regulation and an open-circuit voltage of 28 V D.C. |
| A. | 26.67 V |
| B. | 46.15 V |
| C. | 25 V |
| D. | 16 V |
| Answer» B. 46.15 V | |
| 141. |
Find the transfer function of the given network. |
| A. | \(\dfrac{V_0\left( s\right)}{V_i\left( s\right)}=\dfrac{RC}{s+RC}\) |
| B. | \(\dfrac{V_0\left( s\right)}{V_i\left( s\right)}=\dfrac{1+\dfrac{1}{RC}}{s+\dfrac{1}{RC}}\) |
| C. | \(\dfrac{V_0\left( s\right)}{V_i\left( s\right)}=\dfrac{\dfrac{1}{RC}}{s+\dfrac{1}{RC}}\) |
| D. | \(\dfrac{V_0\left( s\right)}{V_i\left( s\right)}=\dfrac{1+\dfrac{1}{RC}}{s-\dfrac{1}{RC}}\) |
| Answer» D. \(\dfrac{V_0\left( s\right)}{V_i\left( s\right)}=\dfrac{1+\dfrac{1}{RC}}{s-\dfrac{1}{RC}}\) | |
| 142. |
An alternating current is given by i = 20 sin 157t A. The frequency of the alternating current is ________. |
| A. | 100 Hz |
| B. | 75 Hz |
| C. | 25 Hz |
| D. | 50 Hz |
| Answer» D. 50 Hz | |
| 143. |
Consider two nodes A and B connected by an impedance of j5 Ω. If the voltages at nodes A and B are 100∠30° V and 100∠0° V respectively, the real power that can be transferred from node A to B is |
| A. | 1120 W |
| B. | 1000 W |
| C. | 2769 W |
| D. | 276.9 W |
| Answer» C. 2769 W | |
| 144. |
Match the following list:List - IList – IIa) Crest factori) \(\sqrt {\frac{{I_s^2 - I_{s1}^2}}{{I_{s1}^2}}}\) b) Harmonic factorii) cos ϕc) Displacement power factoriii) \(\frac{{{\rm{\Delta }}{{\rm{V}}_0}}}{{{V_0}\left( {average} \right)}}\) d) Power factoriv) \(\frac{{{I_s}\left( {Peak} \right)}}{{{I_s}}}\) Correct code are: |
| A. | (a) – (ii), (b) – (iii), (c) – (iv), (d) – (i) |
| B. | (a) – (iv), (b) – (i), (c) – (ii), (d) – (iii) |
| C. | (a) – (iii), (b) – (iv), (c) – (i), (d) – (ii) |
| D. | (a) – (iv), (b) – (ii), (c) – (i), (d) – (iii) |
| Answer» C. (a) – (iii), (b) – (iv), (c) – (i), (d) – (ii) | |
| 145. |
Consider the R - L - C network shown belowThe average power absorbed by the Inductor in Watts is |
| A. | + 40 |
| B. | 15 |
| C. | 0 |
| D. | 5 |
| Answer» D. 5 | |
| 146. |
In the circuit shown, the power consumed through 5 Ω resistor is 10 W. Then the power factor of circuit is |
| A. | 0.8 |
| B. | 0.6 |
| C. | 0.4 |
| D. | 0.2 |
| Answer» C. 0.4 | |
| 147. |
Find the power p(t), supplied by the element when v(t) = 4 cos 3t V and \(i\left( t \right) = \frac{1}{{12}}\sin 3t\;A\). |
| A. | \(p\left( t \right) = \frac{1}{6}\cos 6t~W\) |
| B. | \(p\left( t \right) = \frac{1}{6}\sin 3t~W\) |
| C. | \(p\left( t \right) = \frac{1}{{12}}\sin 6t~W\) |
| D. | \(p\left( t \right) = \frac{1}{6}\sin 6t~W\) |
| Answer» E. | |
| 148. |
If Phasors P1 = 3 + j4 and P2 = 6 - j8, then | P1 - P2 | is |
| A. | 5 |
| B. | √53 |
| C. | √73 |
| D. | √153 |
| Answer» E. | |
| 149. |
Domestic supply of electricity in India is 220 V AC. 220 V refers to the ______ of the voltage. |
| A. | RMS value |
| B. | Peak value |
| C. | Mean value |
| D. | Minimum value |
| Answer» B. Peak value | |
| 150. |
For the circuit shown below, the voltage (in V) across 4 mF capacitor is ________. |
| A. | 37.3 |
| B. | 3.73 |
| C. | 0.373 |
| D. | 37 |
| Answer» C. 0.373 | |