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MCQOPTIONS
This section includes 1800 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
To find the current in a 20 Ω resistance connected in a circuit, Norton's theorem is used. IN = 7.5 A. The current though 20 Ω resistance. |
| A. | is 7.5 A |
| B. | is less than 7.5 A |
| C. | may be 7.5 A or less |
| D. | may be 7.5 A or more or less |
| Answer» C. may be 7.5 A or less | |
| 152. |
In figure the voltage drop across the 10 Ω resistance is 10 V. The resistance R |
| A. | is 6 Ω |
| B. | is 8 Ω |
| C. | is 4 Ω |
| D. | cannot be found |
| Answer» B. is 8 Ω | |
| 153. |
A resistance of 5 ohms is connected in one branch of a network. The current in this branch is 2.2. A. If the resistance is increased to 7.5 Ω, the remaining circuit being the same, the current in this branch will be |
| A. | 2.2 A |
| B. | less than 2.2 A |
| C. | 2.2 A or less than 2.2 A |
| D. | 2.2 A or less or more than 2.2 A |
| Answer» C. 2.2 A or less than 2.2 A | |
| 154. |
The frame of electric motor is connected to three plates having earthing resistance of 10 Ω, 20 Ω and 30 Ω respectively. The materials of the three plates are copper, aluminium and iron respectively. The percentage of energy dissipated by 10 Ω earthing plate |
| A. | is more than 50% of total energy |
| B. | is less than 50% of total energy |
| C. | depends on the materials of the three plates |
| D. | may be more or less than 50% of total energy |
| Answer» B. is less than 50% of total energy | |
| 155. |
The resistance of the aluminium conductor (r = 2.83 x 10-8 Ωm) in figure is |
| A. | 0.001 Ω |
| B. | less than 0.001 Ω |
| C. | more than 0.001 Ω |
| D. | more than 0.002 Ω |
| Answer» C. more than 0.001 Ω | |
| 156. |
An RLC series circuit has R = 30 Ω, XL = 30 Ω and XC = 30 W. Its impedance is |
| A. | 30 ∠0°. |
| B. | 30 ∠45° |
| C. | 42.42 ∠45° |
| D. | 90 ∠45°. |
| Answer» B. 30 ∠45° | |
| 157. |
An RLC series circuit is excited by 200 V, 100 Hz supply. The current is 20 A. If R = 10 Ω, XL = 50 Ω, XC is |
| A. | 10 Ω |
| B. | 14.14 Ω |
| C. | 7.07 Ω |
| D. | 50 Ω |
| Answer» E. | |
| 158. |
In an R-L circuit, the impedance is 30 Ω at a frequency of 100 Hz. At 200 Hz, the impedance should be |
| A. | 30 Ω or more |
| B. | 60 Ω or more |
| C. | 15 Ω or less |
| D. | more than 30 Ω but less than 60 Ω |
| Answer» E. | |
| 159. |
In an R-C circuit, the impedance is 40 Ω at a frequency of 100 Hz. At 200 Hz the impedance should be |
| A. | 40 Ω |
| B. | 80 Ω |
| C. | 20 Ω |
| D. | more than 20 Ω but less than 40 Ω |
| Answer» E. | |
| 160. |
If A = 7 ∠15, A2 is |
| A. | 49 ∠225° |
| B. | 49 ∠30° |
| C. | 49 ∠15° |
| D. | 49 ∠7.5° |
| Answer» C. 49 ∠15° | |
| 161. |
If V = 100 ∠ 16°, the (V) is |
| A. | 10 ∠ 32° |
| B. | 10 ∠ 8° |
| C. | 10 ∠ 16° |
| D. | 10 ∠ 4° |
| Answer» C. 10 ∠ 16° | |
| 162. |
Three resistance of 15 Ω each are connected in delta. The resistance of equivalent star will have a value of |
| A. | 15 Ω |
| B. | 5 Ω |
| C. | 5/3 Ω |
| D. | 45 Ω |
| Answer» C. 5/3 Ω | |
| 163. |
A circuit is replaced by its Thevenin's equivalent to find current through a certain branch. If VTH = 10 V and RTH = 20 Ω, the current through the branch |
| A. | will always be 0.5 A |
| B. | will always be less than 0.5 A |
| C. | will always be equal to or less than 0.5 A |
| D. | may be 0.5 A or more or less |
| Answer» D. may be 0.5 A or more or less | |
| 164. |
The current through a 10 Ω resistance in a dc circuit having two emf sources is 3A. If this resistance is changed to 20 Ω, the new value of current will be |
| A. | less than 3 A |
| B. | equal or less than 3 A |
| C. | equal to or less or more than 3 A |
| D. | 1.5 A |
| Answer» B. equal or less than 3 A | |
| 165. |
An air cored coil has an inductance of 0.3 H. If another coil has an iron core of μr = 500, the remaining quantities being the same, the inductance of the second coil will be |
| A. | 0.3 H |
| B. | 0.3 x 500 H |
| C. | [C]. |
| D. | none of the above |
| Answer» E. | |
| 166. |
A parallel plate capacitor with air as dielectric has a capacitance C. If the dielectric has a dielectric constant ∈r and the remaining dimensions are the same, the capacitance will be |
| A. | C/∈r |
| B. | ∈rC |
| C. | ∈2rC |
| D. | ∈3rC |
| Answer» C. ∈2rC | |
| 167. |
A conductor has a cylindrical shape with a diameter d. Its resistance is 2 Ω. It is recast into a cylindrical conductor of diameter 0.3d. The resistance of new conductor is likely to be |
| A. | less than 2 Ω |
| B. | less than 0.6 Ω |
| C. | between 2 and 100 Ω |
| D. | more than 100 Ω |
| Answer» E. | |
| 168. |
Three resistances of 15 Ω, 10 Ω and 3 Ω are connected in parallel. The overall resistance is |
| A. | less than 3 Ω |
| B. | between 15 and 10 Ω |
| C. | between 10 and 3 Ω |
| D. | more than 3 Ω |
| Answer» B. between 15 and 10 Ω | |
| 169. |
Two resistances of 2 Ω each are connected in series. A shunt having zero resistance is connected across the combination. The overall resistance will be |
| A. | 4 Ω |
| B. | 1 Ω |
| C. | 0.5 Ω |
| D. | zero |
| Answer» E. | |
| 170. |
A resistor is rated at 0.75 watt, 1 kΩ. Its current rating is |
| A. | 1 mA |
| B. | 27.386 mA |
| C. | 1.268 mA |
| D. | 5.393 mA |
| Answer» C. 1.268 mA | |
| 171. |
This mention statement is associated with “Any number of current sources in parallel may be replaced by a single current source whose current is the algebraic sum of individual currents and source resistance is the parallel combination of individual source resistances”. |
| A. | hevenin’s theorem |
| B. | illman’s theorem |
| C. | aximum power transfer theorem |
| D. | one of the above |
| Answer» C. aximum power transfer theorem | |
| 172. |
This mention statement is associated with “In any network containing more than one sources of e.m.f. the current in any branch is the algebraic sum of a number of individual currents (the number being equal to the number of sources of e.m.f.), each of which is due to separate action of each source of e.m.f., taken order, when the remaining sources of e.m.f. are replaced by conductors, the resistances of which are equal to the internal resistances of the respective sources”. |
| A. | hevenin’s theorem |
| B. | orton’s theorem |
| C. | uperposition theorem |
| D. | one of the above |
| Answer» D. one of the above | |
| 173. |
While calculating Rth in Thevenin’s theorem and Norton equivalent |
| A. | ll independent sources are made dead |
| B. | nly current sources are made dead |
| C. | nly voltage sources are made dead |
| D. | ll voltage and current sources are made dead |
| Answer» B. nly current sources are made dead | |
| 174. |
A star circuit has element of resistance R/2. The equivalent delta elements will be |
| A. | /6 |
| B. | IG |
| C. | /2R |
| D. | R |
| Answer» D. R | |
| 175. |
A network which contains one or more than one source of e.m.f. is known as |
| A. | inear network |
| B. | onlinear network |
| C. | assive network |
| D. | ctive network |
| Answer» E. | |
| 176. |
For the circuit of figure, the time constant is |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» B. B | |
| 177. |
A series R-L circuit has R = 1 Ω and L = 1 H. It is excited by a V battery at t = 0. The steady state condition is reached at |
| A. | t = 1 s |
| B. | t = 0.1 s |
| C. | t = 0 s |
| D. | t = ∞ |
| Answer» E. | |
| 178. |
Which of the following is correct? The circuit shown in the figure.1. is reciprocal but not symmetrical2. is not reciprocal but symmetrical3. both reciprocal and symmetrical4. neither reciprocal nor symmetrical |
| A. | 1, 2 and 3 |
| B. | 2, 3 and 4 |
| C. | 1, 3 and 4 |
| D. | 1, 2 and 4 |
| Answer» B. 2, 3 and 4 | |
| 179. |
Three impedances (3 + j 4) Ω each are connected in star. The impedances of equivalent delta circuit will be |
| A. | 3 - j 4 Ω each |
| B. | 9 + j 12 Ω each |
| C. | 9 - j 12 Ω each |
| D. | 3 + j 4, 3 - j 4 and 4 - j 3 Ω |
| Answer» C. 9 - j 12 Ω each | |
| 180. |
Two capacitors of 1 μF and 2 μF are connected in series across a 10 V dc battery. After the capacitors have been charged, the charges across the two capacitors will be |
| A. | 10 μC each |
| B. | 20 μC each |
| C. | 10 μC and 20 μC |
| D. | 20 μC and 10 μC |
| Answer» C. 10 μC and 20 μC | |
| 181. |
Wave A = 100 sin ωt and wave B = 100 cos ωt. Then |
| A. | rms values of the two waves are equal |
| B. | rms values of A is more than that of B |
| C. | rms values of A is less than that of B |
| D. | rms values of the two waves may or may not be equal |
| Answer» B. rms values of A is more than that of B | |
| 182. |
A two branch parallel tuned circuit has 100 Ω resistance and 0.1 H inductance in one branch and 10¯⁶ F capacitor in the other. At resonance frequency, the dynamic resistance is |
| A. | 10 Ω |
| B. | 100 Ω |
| C. | 1000 Ω |
| D. | 10000 Ω |
| Answer» D. 10000 Ω | |
| 183. |
Which one of the following is positive real function? |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» B. B | |
| 184. |
The synthesis of minimum function was suggested by |
| A. | O'Brune |
| B. | R. Richards |
| C. | Bott and Duffin |
| D. | none of the above |
| Answer» B. R. Richards | |
| 185. |
In a series RLC circuit, R = 2 kΩ, L = 1H and C = µf/400. The resonant frequency is |
| A. | 2 x 10⁴ Hz |
| B. | 1/π x 10⁴ Hz |
| C. | 10⁴ Hz |
| D. | 2π x 10⁴ Hz |
| Answer» C. 10⁴ Hz | |
| 186. |
A coil has resistance R and inductance L. At ω = ∞ the phase angle between voltage and current is |
| A. | 0° |
| B. | 180° |
| C. | 45° |
| D. | 90° |
| Answer» E. | |
| 187. |
Heat in calories = I²Rt/4.186. |
| A. | True |
| B. | False |
| C. | May be True or False |
| D. | Can't say |
| Answer» B. False | |
| 188. |
For the network in figure, which of the following expressions gives the value of net inductance between terminals A and B1. L1 ± L22. L1 ± L2 ± M3. L1 ± L2 - 2M4. L1 ± L2 ± 2MSelect the answer using the following codes |
| A. | 1 only |
| B. | 1 and 2 |
| C. | 3 and 4 |
| D. | 2 and 4 |
| Answer» C. 3 and 4 | |
| 189. |
The flux linkage ψ, self inductance L and current i are related as |
| A. | ψ = L/i |
| B. | ψ = Li |
| C. | ψ = Li² |
| D. | ψ = 0.5Li² |
| Answer» D. ψ = 0.5Li² | |
| 190. |
Assertion (A): The polynomial s³ + 6s² + 12s + 8 is Hurwitz.Reason (R): In a Hurwitz polynomial all coefficients are non-negative. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true and R is not the correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true and R is not the correct explanation of A | |
| 191. |
Two wires A and B have the same cross-section area and are made of the same material. RA = 600 Ω and RB = 100 Ω. The number of times A is longer than B is |
| A. | 6 |
| B. | 2 |
| C. | 4 |
| D. | 5 |
| Answer» B. 2 | |
| 192. |
Steady state conditions are considered to be achieved in R-L circuits at the end of __________ time constant. |
| A. | one |
| B. | two |
| C. | four |
| D. | five |
| Answer» E. | |
| 193. |
The switch in figure is initially closed. At t = 0 the switch is opened. At t = 0+, the current through inductance is |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» D. D | |
| 194. |
If the transfer function has zeros only on jω axis or in left half plane, it is a minimum phase function. |
| A. | True |
| B. | False |
| C. | May be True or False |
| D. | can't say |
| Answer» B. False | |
| 195. |
A specimen of a material has a resistivity of 1.78 x 10⁸ ohm-m. The material is |
| A. | semiconductor |
| B. | conductor |
| C. | semiconductor or conductor |
| D. | insulator |
| Answer» E. | |
| 196. |
Assertion (A): In an R-L circuit having low resistance, current lags the voltage by nearly 90°.Reason (R): Power factor of a series RL circuit is R/Z. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true and R is not the correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true and R is not the correct explanation of A | |
| 197. |
In the Bode plot, of H(s) = 1 + s/20, the phase at w = 15 is |
| A. | ∞ |
| B. | 45 |
| C. | 40 |
| D. | 36.8 |
| Answer» E. | |
| 198. |
For a reactance function H(s), the slope dH (jω)/dω is |
| A. | 0 |
| B. | always positive |
| C. | always negative |
| D. | either 0 or positive |
| Answer» C. always negative | |
| 199. |
A delta connection contains three impedances of 60 Ω each. The impedances of equivalent star connection will be |
| A. | 15 Ω |
| B. | 20 Ω |
| C. | 30 Ω |
| D. | 40 Ω |
| Answer» C. 30 Ω | |
| 200. |
A 1 μF capacitor is connected to 12 V battery. The energy stored in the capacitor is |
| A. | 12 x 10¯⁶ J |
| B. | 24 x 10¯⁶ J |
| C. | 48 x 10¯⁶ J |
| D. | 72 x 10¯⁶ J |
| Answer» E. | |