MCQOPTIONS
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MCQOPTIONS
This section includes 204 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
Due to non sinusoidal waveform of the input current, the power factor of the rectifier is____________? |
| A. | Negatively affected by firing angle |
| B. | Negatively affected by distortion of the input current |
| C. | Positively affected by both firing angle and distortion of the input current |
| D. | Both (a) and (b) |
| Answer» E. | |
| 152. |
Double fourier series analysis of PWM is_____________? |
| A. | Two dimensional functions |
| B. | Three dimensional functions |
| C. | One dimensional functions |
| D. | All of these |
| Answer» B. Three dimensional functions | |
| 153. |
Double edge modulation eliminates certain harmonics when the reference is a__________? |
| A. | Sine wave |
| B. | Square wave |
| C. | Triangular wave |
| D. | Trapezoidal wave |
| Answer» B. Square wave | |
| 154. |
DIAC are specifically designed to trigger______________? |
| A. | TRIAC |
| B. | SCR |
| C. | GTO |
| D. | Only (a) and (b) |
| Answer» E. | |
| 155. |
DIAC and TRIAC both are semiconductors devices and conduct in____________________? |
| A. | DIAC conducts in forward direction and TRIAC conducts in reverse direction |
| B. | Both conducts in forward direction |
| C. | Both conducts in reverse direction |
| D. | Both conducts in either direction |
| Answer» E. | |
| 156. |
Delay time is defined by the interval when_______________? |
| A. | gate current increases from 90 % to 100 % of its final value |
| B. | anode current reaches 10 % from forward leakage current |
| C. | anode voltage drops from 100 % to 90 % of its actual value |
| D. | all of these |
| Answer» E. | |
| 157. |
COOLMOS device can be used in application up to power range of___________? |
| A. | 1 KVA |
| B. | 2 KVA |
| C. | 500 VA |
| D. | 100 KVA |
| Answer» C. 500 VA | |
| 158. |
Compared to transistor, _________ have lower on state conduction losses and higher power handling capability? |
| A. | TRIACs |
| B. | Semi conductor diodes |
| C. | MOSFETs |
| D. | Thyristor |
| Answer» E. | |
| 159. |
Choppers is a_______________? |
| A. | AC – DC converters |
| B. | AC – AC converters |
| C. | DC – AC converters |
| D. | DC – DC converters |
| Answer» E. | |
| 160. |
CB used for over current protection of thyristor operates when the fault current is__________? |
| A. | of long period |
| B. | of short duration |
| C. | both (A) and (B) |
| D. | neither (A) nor (B) |
| Answer» B. of short duration | |
| 161. |
By which one of the following we can measure the reliability of a string_____________? |
| A. | String efficient |
| B. | Reliability factor |
| C. | Factor of safety |
| D. | Derating factor |
| Answer» E. | |
| 162. |
Bidirectional semiconductor device is___________? |
| A. | Diode |
| B. | BJT |
| C. | SCR |
| D. | TRIAC |
| Answer» E. | |
| 163. |
BCT is used for____________? |
| A. | High power phase control |
| B. | High power current control |
| C. | Low power current control |
| D. | Low power phase control |
| Answer» B. High power current control | |
| 164. |
As the breakdown voltage reached, the DIAC exhibits? |
| A. | Negative resistance characteristics |
| B. | Goes into avalanche condition |
| C. | Voltage drop snaps back |
| D. | All of these |
| Answer» E. | |
| 165. |
Any electrical signal present in a circuit other than the desired signal is known as______________? |
| A. | Noise |
| B. | Distortion |
| C. | Interference |
| D. | All of these |
| Answer» B. Distortion | |
| 166. |
Anode current in an SCR consists of____________? |
| A. | holes only |
| B. | electrons only |
| C. | either electron or holes |
| D. | Both electron and holes |
| Answer» B. electrons only | |
| 167. |
Anode of an operational SCR is _______________? |
| A. | Always positive w.r.t cathode |
| B. | Always negative w.r.t anode |
| C. | Always positive w.r.t anode |
| D. | Always negative w.r.t cathode |
| Answer» B. Always negative w.r.t anode | |
| 168. |
An SCR is made up of silicon because? |
| A. | silicon has large leakage current than germanium |
| B. | silicon has small leakage current than germanium |
| C. | silicon has small leakage voltage than germanium |
| D. | silicon has large leakage voltage than germanium |
| Answer» C. silicon has small leakage voltage than germanium | |
| 169. |
An SCR is made up of silicon because_____________? |
| A. | silicon has large leakage current than germanium |
| B. | silicon has small leakage current than germanium |
| C. | silicon has small leakage voltage than germanium |
| D. | silicon has large leakage voltage than germanium |
| Answer» C. silicon has small leakage voltage than germanium | |
| 170. |
An SCR is considered to be a semi controlled device because_______? |
| A. | it can be turned OFF but not ON with a gate pulse |
| B. | it conducts only during one half cycle of an alternating current wave |
| C. | it can be turned ON but not OFF with a gate pulse |
| D. | it can be turned ON only during one half cycle of an AC |
| Answer» D. it can be turned ON only during one half cycle of an AC | |
| 171. |
An SCR has half cycle surge current rating of 3000 A for 50 Hz supply. One cycle surge current will be_____? |
| A. | 1500 A |
| B. | 6000 A |
| C. | 2121.32 A. |
| D. | 4242.64 A. |
| Answer» D. 4242.64 A. | |
| 172. |
An SCR can be used___________? |
| A. | as static conductor |
| B. | for power control |
| C. | for speed control of dc shunt motor |
| D. | All of these |
| Answer» E. | |
| 173. |
An RC snubber network used in BJT__________? |
| A. | Divert the collector current during turn – off |
| B. | Improves the reverse bias safe operating area |
| C. | Dissipates a fair amount of switching power |
| D. | All of these |
| Answer» E. | |
| 174. |
An ideal switch is___________? |
| A. | Lossless |
| B. | Carry current in any direction when it is on |
| C. | Does not carry any current in any direction when it is off |
| D. | All of these |
| Answer» E. | |
| 175. |
An ideal diode is___________? |
| A. | Unidirectional |
| B. | Bidirectional |
| C. | Fixed voltage polarity |
| D. | Only (a) and (c) |
| Answer» E. | |
| 176. |
After proper turn on of thyristor____________? |
| A. | gate signal is always present |
| B. | gate signal must be removed |
| C. | gate signal should present but can be removed |
| D. | none of the above |
| Answer» C. gate signal should present but can be removed | |
| 177. |
Advantages of HVDC transmission over AC system is / are____________? |
| A. | Reversal of power can be controlled by firing angle |
| B. | Very good dynamic behavior |
| C. | They can link two AC system operating unsynchronized |
| D. | All of these |
| Answer» E. | |
| 178. |
Advantages of Cuk converter is / are_____________? |
| A. | Large number of reactive component |
| B. | Low stress on switch |
| C. | Low stress on capacitor |
| D. | None of these |
| Answer» E. | |
| 179. |
AC power in a load can be controlled by using____________? |
| A. | Two SCR’s in parallel opposition |
| B. | Two SCR’s in series |
| C. | Three SCR’s in series |
| D. | Four SCR’s in series |
| Answer» B. Two SCR’s in series | |
| 180. |
AC power in a load can be controlled by using_____________? |
| A. | two SCR’s in parallel opposition |
| B. | two SCR’s in series |
| C. | three SCR’s in series |
| D. | four SCR’s in series |
| Answer» B. two SCR’s in series | |
| 181. |
A Triac has three terminals viz ___________? |
| A. | Drain, source, gate |
| B. | Two main terminal and a gate terminal |
| C. | Cathode, anode, gate |
| D. | None of the above |
| Answer» C. Cathode, anode, gate | |
| 182. |
A Triac is a ______________? |
| A. | 2 terminal switch |
| B. | 2 terminal bilateral switch |
| C. | 3 terminal bilateral switch |
| D. | 3 terminal bidirectional switch |
| Answer» E. | |
| 183. |
A TRIAC can be turned on with______________? |
| A. | Positive voltage at the gate terminal |
| B. | Negative voltage at the gate terminal |
| C. | Either (a) or (b) |
| D. | None of these |
| Answer» D. None of these | |
| 184. |
A thyristor string is made of a no. of SCR connected in series and parallel. The string have volume and current of 11 KV and 4 KA. The voltage and current rating of available SCRs are 1800 V and 1000 A. For a string efficiency of 90 % let the number of SCRs in series and parallel are a and b respectively. Then the value of a and b will be_____________? |
| A. | 5, 7 |
| B. | 4, 6 |
| C. | 7, 5 |
| D. | 6, 4 |
| Answer» D. 6, 4 | |
| 185. |
A thyristor can termed as__________? |
| A. | AC switch |
| B. | DC switch |
| C. | Both a and B |
| D. | Square wave switch |
| Answer» C. Both a and B | |
| 186. |
A thyristor is basically________? |
| A. | PNPN device |
| B. | A combination of diac and triac |
| C. | A set of SCRs |
| D. | A set if SCR,diac and triac |
| Answer» B. A combination of diac and triac | |
| 187. |
A thyristor equivalent of a thyratron tube is a _________? |
| A. | Diac |
| B. | Triac |
| C. | Silicon controlled-rectifier SCR |
| D. | None of above |
| Answer» D. None of above | |
| 188. |
A string of n parallel SCRs is operated at 72 KA, the rating of each SCR is 1 KA. If derating factor of the string is 0.1. value of n will be___________? |
| A. | 60 |
| B. | 70 |
| C. | 80 |
| D. | 90 |
| Answer» D. 90 | |
| 189. |
A step up chopper has input voltage 110 V and output voltage 150 V. The value of duty cycle is_____? |
| A. | 0.32 |
| B. | 0.67 |
| C. | 0.45 |
| D. | 0.27 |
| Answer» E. | |
| 190. |
A step – down choppers can be used in___________? |
| A. | Electric traction |
| B. | Electric vehicles |
| C. | Machine tools |
| D. | All of these |
| Answer» E. | |
| 191. |
A single phase one pulse controlled circuit has a resistance R and counter emf E load 400 sin(314 t) as the source voltage. For a load counter emf of 200 V, the range of firing angle control is _____? |
| A. | 30° to 150°. |
| B. | 30° to 180°. |
| C. | 60° to 120°. |
| D. | 60° to 180°. |
| Answer» B. 30° to 180°. | |
| 192. |
A single phase full bridge inverter can operated in load commutation mode in case load consist of______? |
| A. | RL. |
| B. | RLC underdamped |
| C. | RLC overdamped |
| D. | RLC critically damped |
| Answer» C. RLC overdamped | |
| 193. |
A single phase full bridge inverter can operate in load commutation mode in case load consists of____________? |
| A. | RL |
| B. | RLC underdamped |
| C. | RLC overdamped |
| D. | RLC critically damped |
| Answer» C. RLC overdamped | |
| 194. |
A single phase ac – dc converter is also known as____________? |
| A. | rectifier |
| B. | inverter |
| C. | chopper |
| D. | regulator |
| Answer» B. inverter | |
| 195. |
A silicon controlled racitifier (SCR) is a ____________? |
| A. | Unijunction device |
| B. | Device with three junction |
| C. | Device with four junction |
| D. | None of the above |
| Answer» C. Device with four junction | |
| 196. |
A rectifier with an external low pass filter is an example of______________? |
| A. | Indirect switch matrix circuits |
| B. | Direct switch matrix circuits |
| C. | Embedded converters |
| D. | All of these |
| Answer» C. Embedded converters | |
| 197. |
A power semiconductor may undergo damage due to____________? |
| A. | High di/dt |
| B. | High dv/dt |
| C. | Low di/dt |
| D. | Low dv/dt |
| Answer» B. High dv/dt | |
| 198. |
A power MOSFET has three terminals called___________? |
| A. | Collector, emitter and gate |
| B. | Drain, source and gate |
| C. | Drain, source and base |
| D. | Collector, emitter and base |
| Answer» C. Drain, source and base | |
| 199. |
A PNPN device having two gates is ___________? |
| A. | Diac |
| B. | Triac |
| C. | SUS |
| D. | BCS |
| Answer» E. | |
| 200. |
A MOSFET, for its conduction uses_____________? |
| A. | Only minority carriers |
| B. | Only majority carriers |
| C. | Both minority and majority carriers |
| D. | None of these |
| Answer» C. Both minority and majority carriers | |