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.
| 351. |
In an ac coordinate potentiometer, the currents inphase and quadrature potentiometer are adjusted to be |
| A. | out of phase by 90° |
| B. | in phase |
| C. | out of phase by 45° |
| D. | out of phase 180° |
| Answer» B. in phase | |
| 352. |
It is necessary to measure the amplitudes of two signals and also the phase difference between them. This can be done by using a |
| A. | phase meter |
| B. | waveform meter |
| C. | vector voltmeter |
| D. | digital voltmeter |
| Answer» C. vector voltmeter | |
| 353. |
Eddy currents are essential for the deflecting torque of an induction wattmeter. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 354. |
Radiation pyrometer is used to measure temperature in the range of |
| A. | -200 to 500° C |
| B. | 0 to 500° C |
| C. | 500 to 1200° C |
| D. | 1200 to 2500° C |
| Answer» E. | |
| 355. |
The input impedance of CRO is about |
| A. | zero |
| B. | 10 Ω |
| C. | 100 Ω |
| D. | one mega ohm |
| Answer» E. | |
| 356. |
A high resistance was measured by loss of charge method. The voltmeter resistance was 1010 ohms. The calculation gave the value of unknown resistance as 0.8 x 109 ohms. The true value of resistance is |
| A. | 0.8 x 109 Ω |
| B. | less than 0.8 x 109 Ω |
| C. | more than 0.8 x 109 Ω |
| D. | either (b) or (c) |
| Answer» D. either (b) or (c) | |
| 357. |
The scale of moving iron instrument is linear. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 358. |
For a current transformer, the standard secondary rating is |
| A. | 1 A or 5 A |
| B. | 2.5 A |
| C. | 0.41666666666667 |
| D. | 5 A or 10 A |
| Answer» B. 2.5 A | |
| 359. |
When measuring phase angle between two waves using a CRO, the time base generator is connected to |
| A. | X plate |
| B. | Y plate |
| C. | both X and Y plate |
| D. | neither X nor Y plates |
| Answer» E. | |
| 360. |
A 3-digit voltmeter having a resolution of 100 mV can be used to measure a maximum of |
| A. | 100 V |
| B. | 200 V |
| C. | 1000 V |
| D. | 5000 V |
| Answer» B. 200 V | |
| 361. |
A moving iron instrument has |
| A. | two iron vanes, one fixed and one movable |
| B. | two movable iron vanes |
| C. | two aluminium vanes, one fixed and one movable |
| D. | two vanes, one fixed made of Aluminium and the other movable made of iron |
| Answer» B. two movable iron vanes | |
| 362. |
Capacitive transducer is superior to inductive type for measurement of capacitance because of |
| A. | absence of non-linearity |
| B. | high frequency response |
| C. | small size |
| D. | high accuracy |
| Answer» C. small size | |
| 363. |
An ohmmeter is a |
| A. | moving coil instrument |
| B. | moving iron instrument |
| C. | dynamometer instrument |
| D. | induction instrument |
| Answer» B. moving iron instrument | |
| 364. |
The time base of a high frequency CRO whose screen diameter is 10 cm is set at 10 μ sec/cm. The lowest frequency which can be fully displayed on the screen is |
| A. | more than 100 kHz |
| B. | equal to 100 kHz |
| C. | equal to 10 kHz |
| D. | less than 10 kHz |
| Answer» D. less than 10 kHz | |
| 365. |
Rayleigh current balance is an absolute instrument. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 366. |
The power factor of a single phase load can be calculated if instruments available are |
| A. | one voltmeter, one ammeter |
| B. | two ammeters |
| C. | two voltmeters |
| D. | one voltmeter, one ammeter and one wattmeter |
| Answer» E. | |
| 367. |
A resistance wire strain gauge has gauge factor 2. If stress is 100 mega newton/m2 and Young's modulus is 200 giga newton/ m2, the percentage change in gauge resistance due to stress is |
| A. | 0.1 |
| B. | 0.2 |
| C. | 0.4 |
| D. | 0.5 |
| Answer» B. 0.2 | |
| 368. |
A D' Arsonval galvanometer is a |
| A. | moving coil instrument |
| B. | moving iron instrument |
| C. | dynamometer instrument |
| D. | induction instrument |
| Answer» B. moving iron instrument | |
| 369. |
A current of 3.18 A is flowing through resistance of 35.68 Ω. The voltage drop across resistance to the appropriate number of significant figures is |
| A. | 113.4624 V |
| B. | 113.462 V |
| C. | 113.46 V |
| D. | 113 V |
| Answer» E. | |
| 370. |
Minute cracks in metals and minute faults in welded joints can be detected using |
| A. | IR rays |
| B. | UV rays |
| C. | a rays |
| D. | X-ray/γ-rays |
| Answer» E. | |
| 371. |
Assertion (A): In hot wire instrument the material of hot wire in generally platinum iridium.Reason (R): A hot wire ammeter is suitable for ac only |
| 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» D. A is false R is true | |
| 372. |
The two pressure coils in a single phase power factor meter of turns |
| A. | the same dimension and the same numbers of turns |
| B. | the same dimension but different number of turns |
| C. | different dimension and different numbers of turns |
| D. | different dimension but the same numbers of turns |
| Answer» B. the same dimension but different number of turns | |
| 373. |
DC voltage of the order of a few mV can be accurately of measured by |
| A. | PMMC voltmeters |
| B. | moving iron voltmeter |
| C. | null balancing potentiometer |
| D. | electrostatic voltmeter |
| Answer» D. electrostatic voltmeter | |
| 374. |
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 backward direction. A moving coil ammeter is also connected in the circuit. The reading of ammeter will be |
| A. | 0.41666666666667 |
| B. | 0.20833333333333 |
| C. | 3.185 A |
| D. | 14.14 A |
| Answer» D. 14.14 A | |
| 375. |
Consider the following statements about mutual inductances: The value should remain constant under all conditions.The mutual inductance should not vary with temperature.The inductance should be independent of excitation.They have two coils wound on a bobbin of hard magnetic material, coils being separated by a range. Out of the above, correct statement are |
| A. | 2, 3, 4 |
| B. | 1, 2, 3 |
| C. | 1, 3, 4 |
| D. | 1, 2, 4 |
| Answer» C. 1, 3, 4 | |
| 376. |
Assertion (A): A radiation pyrometer is very suitable for high temperature measurement.Reason (R): When temperature is high, a physical contact between hot body and thermometer is not desirable. |
| 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 | |
| 377. |
Which of the following is used as detector in audio frequency ac bridges? |
| A. | AC voltmeter |
| B. | CRO |
| C. | Head phones |
| D. | Vibration galvanometer |
| Answer» D. Vibration galvanometer | |
| 378. |
Which instrument is based on induction principle? |
| A. | Dynamometer wattmeter |
| B. | Induction wattmeter |
| C. | Energy meter |
| D. | Both (b) and (c) |
| Answer» E. | |
| 379. |
Acoustic strain gauges |
| A. | have good linearity of measurement |
| B. | do not have long term stability |
| C. | have a large range of measurement |
| D. | have an accuracy range of 0.1-1% depending on environment |
| Answer» E. | |
| 380. |
The resistance in the circuit of the moving coil of a dynamometer wattmeter should be |
| A. | very low |
| B. | low |
| C. | high |
| D. | almost zero |
| Answer» D. almost zero | |
| 381. |
Assertion (A): Moving iron instrument can be used on ac or dc.Reason (R): In a moving iron instrument deflecting torque is proportional to square of current. |
| 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 | |
| 382. |
For measuring a very high resistance we should use |
| A. | Kelvin's double bridge |
| B. | Wheatstone bridge |
| C. | Meggar |
| D. | Either (a) or (c) |
| Answer» D. Either (a) or (c) | |
| 383. |
In a current transformers |
| A. | the number of turns in primary and secondary windings are nearly equal |
| B. | the number of primary turns is very small as compared to number of secondary turns. |
| C. | the number of secondary turns is very small as compared to the number of primary turns |
| D. | either (a) or (c). |
| Answer» C. the number of secondary turns is very small as compared to the number of primary turns | |
| 384. |
The response of D'Arsonval galvanometer is over damped if |
| A. | D2 > 4CJ |
| B. | D2 > 2CJ |
| C. | D2 < 4CJ |
| D. | D2 < 2CJ |
| Answer» B. D2 > 2CJ | |
| 385. |
A resistance strain gauge has a resistance of about |
| A. | 100 Ω |
| B. | 25 Ω |
| C. | 10 Ω |
| D. | 1 Ω |
| Answer» B. 25 Œ© | |
| 386. |
Consider the following statements as regards induction and dynamometer wattmeters Dynamometer wattmeters can be used for dc only.Induction wattmeter has higher torque and dynamometer wattmeter.Induction wattmeter is less accurate, has more power consumption and more weight than dynamometer wattmeter. Which of the above statements are correct? |
| A. | 1 only |
| B. | 1 and 2 only |
| C. | 2 and 3 only |
| D. | 1 and 3 only |
| Answer» D. 1 and 3 only | |
| 387. |
Assertion (A): Maxwell bridge is for measuring inductance of medium magnitude.Reason (R): In Maxwell's bridge the unknown inductance is measured by comparing it with a 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» D. A is false R is true | |
| 388. |
In which of the following instruments is the deflecting torque proportional to where L is inductance of coil and Q is deflection |
| A. | PMMC |
| B. | electrostatic |
| C. | moving iron |
| D. | both (a) and (b) |
| Answer» D. both (a) and (b) | |
| 389. |
In figure, Za = 100∠50°, Zb = 300∠-90° and Zc = 200∠0°. For balanced condition, Zd will be |
| A. | 600∠ - 40° |
| B. | 600∠140° |
| C. | 600∠ - 140° |
| D. | 150∠140° |
| Answer» D. 150‚à†140¬∞ | |
| 390. |
The percentage limiting error in an instrument reading 8.3 V and having guaranteed accuracy of 1% of the full scale reading and range of 0-150 V is |
| A. | 0.0181 |
| B. | 0.0018 |
| C. | 0.181 |
| D. | 0 |
| Answer» D. 0 | |
| 391. |
In a CRO, the frequency of output of time base generator |
| A. | is only one constant value |
| B. | is adjustable |
| C. | varies automatically |
| D. | either (a) or (c) |
| Answer» C. varies automatically | |
| 392. |
A variable reluctance type tachometer has 150 teeth on rotor. The counter records 13500 pulse/sec. The rotational speed is |
| A. | 4800 RPM |
| B. | 5400 RPM |
| C. | 6000 RPM |
| D. | 7200 RPM |
| Answer» C. 6000 RPM | |
| 393. |
In dc tacho generators used for measurement of speed of shaft, frequent calibration is necessary because |
| A. | contacts wear off |
| B. | strength of permanent magnet decreases with age |
| C. | armature current produces heating effect |
| D. | there is back emf |
| Answer» C. armature current produces heating effect | |
| 394. |
Assertion (A): CRT is the most important component of a CRO.Reason (R): When an electron beam strikes the screen of CRT, a spot of light is produced. |
| 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 | |
| 395. |
An E transformer is a |
| A. | displacement transducer |
| B. | velocity transducer |
| C. | acceleration transducer |
| D. | pressure transducer |
| Answer» B. velocity transducer | |
| 396. |
Two voltmeters are each 0-300 V range. Their internal resistances are 10 kΩ and 20 kΩ They are connected is series and a voltage of 400 V is applied. Their readings respectively will be |
| A. | 266.6 and 133.3 V |
| B. | 133.3 and 266.6 V |
| C. | 200 V each |
| D. | 100 and 300 V |
| Answer» C. 200 V each | |
| 397. |
Assertion (A): A low power factor wattmeter has special constructional features to ensure accurate measurement.Reason (R): Extension of wattmeter range in dc circuit can be easily done by using current and potential transformer. |
| 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» D. A is false R is true | |
| 398. |
Which of these instruments has highest power consumption? |
| A. | Dynamometer |
| B. | Electrostatic |
| C. | Moving coil |
| D. | Hot wire |
| Answer» E. | |
| 399. |
A generated voltage is equally dependent on three resistances R1, R2, R3 and its value is V = (R1R2)/R3. If tolerance of each resistor is 0.1%, the maximum error in voltage is |
| A. | 0.003 |
| B. | ± 0.3% |
| C. | 0.001 |
| D. | ± 0.1% |
| Answer» C. 0.001 | |
| 400. |
An electrostatic voltmeter is suitable for |
| A. | low voltage at high frequency |
| B. | high voltage |
| C. | low voltage at low frequency |
| D. | all ac and dc voltages |
| Answer» C. low voltage at low frequency | |