MCQOPTIONS
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MCQOPTIONS
This section includes 571 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.
| 251. |
Which of the following transformers has low primary current? |
| A. | Current transformer |
| B. | Potential transformer |
| C. | Distribution transformer |
| D. | Both (a) and (b) |
| Answer» C. Distribution transformer | |
| 252. |
If σ standard deviation, probable error |
| A. | σ |
| B. | ± 1.19 σ |
| C. | ± 0.6745 σ |
| D. | ± 0.4125 σ |
| Answer» D. ¬± 0.4125 œÉ | |
| 253. |
Figure shows a Wheatstone bridge with RTD to one arm. If resistance of RTD = 1020 Ω, the voltage V0 is |
| A. | 49 mV |
| B. | 51 mV |
| C. | 48 mV |
| D. | 45 mV |
| Answer» B. 51 mV | |
| 254. |
Wagner earthing device eliminates |
| A. | all stray capacitance in the circuit |
| B. | stray capacitances between components |
| C. | stray capacitance between detector terminal and ground |
| D. | mutual coupling between components |
| Answer» D. mutual coupling between components | |
| 255. |
A sinusoidal ac voltage of amplitude 100 V is applied to a rectifying device which offers 10 Ω resistance in forward direction and infinite resistance in reverse direction. The reading on hot wire ammeter will be |
| A. | 0.41666666666667 |
| B. | 0.20833333333333 |
| C. | 3.185 A |
| D. | 1.414 A |
| Answer» C. 3.185 A | |
| 256. |
For measuring mutual inductance we can use |
| A. | Anderson bridge |
| B. | Maxwell's bridge |
| C. | Heaviside bridge |
| D. | Either (a) or (b) |
| Answer» D. Either (a) or (b) | |
| 257. |
In measuring resistance using voltmeter and ammeter, the resistances of voltmeter and ammeter also affect the accuracy of measurement. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 258. |
In a semiconductor strain gauge, the ohmic electrical contacts are generally made of |
| A. | copper wire |
| B. | gold wire |
| C. | aluminium wire |
| D. | nickel wire |
| Answer» C. aluminium wire | |
| 259. |
Which of the following effects is used in measurement of magnetic flux? |
| A. | Hall effect |
| B. | Seeback effect |
| C. | Piezo electric effect |
| D. | Photoelectric effect |
| Answer» B. Seeback effect | |
| 260. |
A moving iron instrument can be used for |
| A. | dc only |
| B. | ac only |
| C. | both dc and ac |
| D. | dc and high frequency ac |
| Answer» D. dc and high frequency ac | |
| 261. |
In ac bridge measurements, 'Wagner ground' means |
| A. | a special RC connection to eliminate stray magnetic effects |
| B. | a special RC connection to eliminate stray capacitance effects |
| C. | an unwanted and unintended ground connection |
| D. | a large metal plate buried in ground connected to one corner of bridge |
| Answer» C. an unwanted and unintended ground connection | |
| 262. |
In Maxwell's bridge the unknown inductance is measured by comparing it with a standard capacitor. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 263. |
The switch board instruments |
| A. | should be mounted in vertical position |
| B. | should be mounted in horizontal position |
| C. | should be mounted at about 45° |
| D. | should be mounted at about 80° |
| Answer» B. should be mounted in horizontal position | |
| 264. |
Which of the following methods can be used to measure power in a single phase circuit without using wattmeter? One voltmeter, one ammeterTwo voltmeters, two ammeterThree voltmetersThree ammeters |
| A. | 1 and 2 only |
| B. | 2 and 4 only |
| C. | 1 and 3 only |
| D. | 3 and 4 only |
| Answer» E. | |
| 265. |
A moving iron instrument can be used for dc as well as ac. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 266. |
If two time varying signals of equal magnitudes and 90° phase displacement are applied to X and Y plates of CRO, the display will be |
| A. | a straight line |
| B. | a circle |
| C. | an ellipse |
| D. | a rectangle |
| Answer» C. an ellipse | |
| 267. |
Harmonic distortion analyser |
| A. | measures amplitude of each harmonic |
| B. | measures rms value of fundamental frequency component |
| C. | measures rms value of all harmonics except fundamental frequency |
| D. | displays rms value of each harmonic on screen of CRO |
| Answer» D. displays rms value of each harmonic on screen of CRO | |
| 268. |
The resistance of series field winding is a low resistance. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 269. |
Two resistances are : R1 = 36 Ω ± 1.89 Ω and R2 = 75 Ω ± 3.75 Ω. The sum R1 + R2 along with limiting error is |
| A. | 111 Ω ± 1.8 Ω |
| B. | 111 Ω ± 3.75 Ω |
| C. | 111 Ω ± 5.55 Ω |
| D. | 111 Ω ± 1.95 Ω |
| Answer» D. 111 Œ© ¬± 1.95 Œ© | |
| 270. |
The dimensions of permittivity are |
| A. | L-3M-1T2Q2 |
| B. | L-1M-1T2Q2 |
| C. | L2MT-1Q-1 |
| D. | L-2M-1T2Q2 |
| Answer» B. L-1M-1T2Q2 | |
| 271. |
Assertion (A): Schering bridge is a low voltage bridge.Reason (R): Schering bridge is very commonly used for measurement of capacitance. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not correct explanation of A |
| C. | A is true R is false |
| D. | A is false R is true |
| Answer» E. | |
| 272. |
A Weston synchronoscope is a |
| A. | moving coils instrument |
| B. | moving iron instrument |
| C. | dynamometer instrument |
| D. | induction instrument |
| Answer» D. induction instrument | |
| 273. |
A 0-150 voltmeter has a guaranteed accuracy of 1% of full scale reading. If actual reading is 83 V, the percentage error is |
| A. | 0.0083 |
| B. | 0.01 |
| C. | 0.0181 |
| D. | none of the above |
| Answer» D. none of the above | |
| 274. |
Which of the following is not a transducer in true sense? |
| A. | Thermocouple |
| B. | Piezo electric |
| C. | Photo electric cell |
| D. | LCD |
| Answer» E. | |
| 275. |
Assertion (A): A semiconductor strain gauge is more accurate than a resistance strain gauge.Reason (R): The gauge factor of a semiconductor strain gauge is about 100 where as the gauge factor of a resistance strain gauge is only about 2. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not correct explanation of A |
| C. | A is true R is false |
| D. | A is false R is true |
| Answer» B. Both A and R are true but R is not correct explanation of A | |
| 276. |
The sensitivity of a voltmeter using 0-5 mA meter movement is |
| A. | 50 Ω/V |
| B. | 100 Ω/V |
| C. | 200 Ω/V |
| D. | 500 Ω/V |
| Answer» D. 500 Œ©/V | |
| 277. |
Four terminal approach is used in measuring low resistance because it |
| A. | eliminates thermoelectric energy |
| B. | eliminates stray capacitance |
| C. | eliminates stray inductance |
| D. | eliminates the effect of leads and contacts |
| Answer» E. | |
| 278. |
The adjustment of position of shading bands, in an energy meter, is done to provide |
| A. | friction compensation |
| B. | creep compensation |
| C. | braking torque |
| D. | none of the above |
| Answer» B. creep compensation | |
| 279. |
Consider the following statements regarding phase sensitive detector The detector reads zero when phases of input signal and reference signal are different.The detector acts as a linear rectifier.The detector can be used as vector voltmeter. Of the above statements which are correct? |
| A. | 1, 2, 3 |
| B. | 1 and 2 |
| C. | 2 and 3 |
| D. | 1 and 3 |
| Answer» D. 1 and 3 | |
| 280. |
In bridge circuit of figure, equivalent resistance between A and B is |
| A. | 1 Ω |
| B. | 0.5 Ω |
| C. | 2 Ω |
| D. | 1.5 Ω |
| Answer» B. 0.5 Œ© | |
| 281. |
Which of the following devices should be used for accurate measurement of a low dc voltage? |
| A. | Small range moving coil voltmeter |
| B. | Dc potentiometer |
| C. | Small range thermocouple voltmeter |
| D. | Hot wire instrument |
| Answer» C. Small range thermocouple voltmeter | |
| 282. |
A coil resonates at 1 MHz with a resonating capacitance of 72 pF. At 500 pF, resonance is obtained with a resonating capacitor of 360 pF. The self capacitance of coil is |
| A. | 12 pF |
| B. | 24 pF |
| C. | 30 pF |
| D. | 72 pF |
| Answer» C. 30 pF | |
| 283. |
The method of frequency compensation in moving iron voltmeter is |
| A. | to use a capacitor in series with coil |
| B. | to connect a capacitor in parallel with coil |
| C. | to connect a capacitor in parallel with series resistance |
| D. | none of the above |
| Answer» D. none of the above | |
| 284. |
Measurement of non-electrical quantity involves the following subsystems Amplifier blockDisplay blockInstrumentation blockTransducer block The correct sequence of these blocks is |
| A. | 4, 1, 3, 2 |
| B. | 4, 3, 1, 2 |
| C. | 1, 3, 2, 4 |
| D. | 1, 2, 3, 4 |
| Answer» B. 4, 3, 1, 2 | |
| 285. |
Induction wattmeter is an absolute instrument. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 286. |
A variable reluctance tachometer has 180 teeth on rotor. The speed of shaft on which it is mounted in 1200 rpm. The frequency of output pulses is |
| A. | 1800 per second |
| B. | 3600 per second |
| C. | 4800 per second |
| D. | 5600 per second |
| Answer» C. 4800 per second | |
| 287. |
The coil of a DArsonval galvanometer has N turns. If flux density is B, current is I and area of coil is A, the deflecting torque is |
| A. | NBI/A |
| B. | NBIA |
| C. | NIA/B |
| D. | N2IAB |
| Answer» C. NIA/B | |
| 288. |
The most serious problems in ac bridge measurement is |
| A. | eddy currents |
| B. | leakage current |
| C. | residual magnetism |
| D. | stray fields |
| Answer» E. | |
| 289. |
An accelerometer has a seismic mass of 0.05 kg and spring constant of 3 x 105 N/m. If maximum displacement of mass is ± 1 mm, the maximum acceleration which can be measured is |
| A. | 30 m/s2 |
| B. | 60 m/s2 |
| C. | 90 m/s2 |
| D. | 120 m/s2 |
| Answer» C. 90 m/s2 | |
| 290. |
Assertion (A): An electrostatic voltmeter is free from hysteresis and eddy current errors.Reason (R): An electrostatic voltmeter has a number of fixed and moving vanes in parallel. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not correct explanation of A |
| C. | A is true R is false |
| D. | A is false R is true |
| Answer» C. A is true R is false | |
| 291. |
The accuracy of an instrument is determined by |
| A. | closeness of indicated value to the actual value |
| B. | repeatability of measured value |
| C. | speed with which the reading approaches final value |
| D. | least value which can be measured |
| Answer» B. repeatability of measured value | |
| 292. |
In air friction damping |
| A. | the air pressure opposes the motion of piston when it is moving inwards |
| B. | the air pressure opposes the motion of piston when it is moving outwards |
| C. | the air pressure opposes the motion of piston both when it is moving inwards as well as outwards |
| D. | the air pressure may oppose or aid the motion of piston depending on the design |
| Answer» D. the air pressure may oppose or aid the motion of piston depending on the design | |
| 293. |
Two resistance R1 and R2 are connected in series R1 = 528 ± 5 Ω and R2 = 325 ± 3Ω. The total resistance will be |
| A. | 853 ± 2 Ω |
| B. | 853 ± 5 Ω |
| C. | 853 ± 3 Ω |
| D. | 853 ± 8 Ω |
| Answer» E. | |
| 294. |
Assertion (A): Capacitance effect can be used to measure thickness of sheets, displacement and pressure.Reason (R): Capacitance between two plates depends on the area of plates, distance between plates and permittivity of medium. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not correct explanation of A |
| C. | A is true R is false |
| D. | A is false R is true |
| Answer» B. Both A and R are true but R is not correct explanation of A | |
| 295. |
For measurement of high voltage capacitors the suitable bridge is |
| A. | Wien bridge |
| B. | modified De Sauty bridge |
| C. | Schering bridge |
| D. | either (a) or (b) |
| Answer» D. either (a) or (b) | |
| 296. |
Which is the displacement transducer with excellent sensitivity, linearity and resolution? |
| A. | Incremental encoder |
| B. | Absolute encoder |
| C. | LVDT |
| D. | Strain gauge |
| Answer» D. Strain gauge | |
| 297. |
The electromagnets of an induction wattmeter |
| A. | are laminated |
| B. | are not laminated |
| C. | may be laminated |
| D. | must not be laminated |
| Answer» B. are not laminated | |
| 298. |
Assertion (A): For best results the system of a D'Arsonval galvanometer should be slightly under damped.Reason (R): Degree of damping affects the time taken by the instrument to come to final position. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not correct explanation of A |
| C. | A is true R is false |
| D. | A is false R is true |
| Answer» C. A is true R is false | |
| 299. |
To measure a resistance by a dc potentiometer |
| A. | it is necessary to standardise the potentiometer |
| B. | it is not necessary to standardise the potentiometer |
| C. | it is necessary to use a volt ratio box |
| D. | none of the above |
| Answer» C. it is necessary to use a volt ratio box | |
| 300. |
A dynamometer wattmeter can be used for |
| A. | dc only |
| B. | ac only |
| C. | dc and 50 Hz ac |
| D. | dc and high frequency ac |
| Answer» D. dc and high frequency ac | |