MCQOPTIONS
Saved Bookmarks
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.
| 101. |
The resistance of resistance strain gauge is about |
| A. | 5 Ω |
| B. | 50 Ω |
| C. | 120 Ω |
| D. | 0.5 Ω |
| Answer» D. 0.5 Œ© | |
| 102. |
A diode peak reading VTVM and thermocouple meter are connected across output of an amplitude modulated circuit. In the absence of modulation both meters read 10 V. When sinusoidal AM is applied, VTVM reads 15V The reading of thermocouple meter will be |
| A. | 10 V |
| B. | 12.5 V |
| C. | 14.1 V |
| D. | 15 V |
| Answer» B. 12.5 V | |
| 103. |
A thermocouple instrument can be used over a very wide frequency range. |
| A. | 1 |
| B. | |
| C. | moving coil instrument |
| D. | moving iron instrument |
| Answer» B. | |
| 104. |
In a Ballistic galvanometer |
| A. | inertia is small and damping is also small |
| B. | inertia is large and damping is critical |
| C. | inertia is large and damping is small |
| D. | both inertia and damping are large |
| Answer» D. both inertia and damping are large | |
| 105. |
If J is moment of Inertia, D is damping constant, C is spring constant, G is displacement constant and I is current throught the coil of DArsonval galvanometer, the equation of motion is |
| A. | |
| B. | |
| Answer» C. | |
| 106. |
Wagner earthing device is used to eliminate error due to |
| A. | electromagnetic coupling |
| B. | electrostatic coupling |
| C. | both electrostatic and electromagnetic coupling |
| D. | either (a) or (b) |
| Answer» C. both electrostatic and electromagnetic coupling | |
| 107. |
The 10 MHz in the specification of CRO means that |
| A. | the sweep frequency is 10 MHz |
| B. | the frequency of input signal should not be more than 10 MHz |
| C. | the vertical amplifier has been designed for 10 MHz |
| D. | none of the above |
| Answer» B. the frequency of input signal should not be more than 10 MHz | |
| 108. |
Assertion (A): A power factor meter operates on dynamometer principle. Reason (R): A power factor meter does not have a control spring. |
| 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 | |
| 109. |
In order to achieve accuracy, the slide wire of a potentiometer should be |
| A. | as long as possible |
| B. | as short as possible |
| C. | neither too long nor too short |
| D. | very thin |
| Answer» B. as short as possible | |
| 110. |
If the current in a capacitor leads the voltage by 80°, the loss angle of capacitor is |
| A. | 80° |
| B. | 10° |
| C. | 100° |
| D. | 170° |
| Answer» C. 100¬∞ | |
| 111. |
In Weston synchronoscope the fixed coils are connected across |
| A. | bus bars |
| B. | incoming alternator |
| C. | lamp |
| D. | either (a) or (b) |
| Answer» C. lamp | |
| 112. |
Four capacitors are in parallel. Their values are 36.3 μF, 3.85 μF, 34.002 μF and 850 μF with an uncertainty of digit in the last place. The total capacitance in significant figures is |
| A. | 75.0 μF |
| B. | 75.0 ± 0.1 μF |
| C. | 75.1 ± 0.1 μF |
| D. | 75.002 ± 0.1 μF |
| Answer» C. 75.1 ¬± 0.1 ŒºF | |
| 113. |
An ammeter is |
| A. | recording instrument |
| B. | integrating instrument |
| C. | chromel constantan |
| D. | iron constantan |
| Answer» B. integrating instrument | |
| 114. |
Measuring of unknown voltage with a dc potentiometer loses its advantage of open circuit measurement when |
| A. | primary circuit battery is changed |
| B. | standardisation is done to compensate for drift |
| C. | voltage is larger than range of potentiometer |
| D. | range reduction by factor of 10 is employed |
| Answer» E. | |
| 115. |
An ammeter has a resistance of 50 ohms and a shunt of 0.01 Ω. The deflection is θ. If the shunt resistance is increased to 0.02 Ω, the deflection will be. |
| A. | 375∠70° Ω |
| B. | 375∠ - 70° Ω |
| C. | 150∠0° Ω |
| D. | 150∠20° Ω |
| Answer» C. 150‚à†0¬∞ Œ© | |
| 116. |
For measuring inductance with high Q, we should use |
| A. | Maxwell's bridge |
| B. | Maxwell Wien bridge |
| C. | Hay's bridge |
| D. | Either (a) or (b) |
| Answer» D. Either (a) or (b) | |
| 117. |
In an ac single phase energy meter, the potential coil is put on |
| A. | both side limbs, of upper magnet |
| B. | central limb of upper magnet |
| C. | one side limb of upper magnet |
| D. | either (a) or (b) |
| Answer» C. one side limb of upper magnet | |
| 118. |
A dual trace CRO has |
| A. | one electron gun |
| B. | two electron guns |
| C. | one electron gun with one two pole switch |
| D. | two electron guns with one two pole switch |
| Answer» D. two electron guns with one two pole switch | |
| 119. |
A temperature sensistive transducer is subjected to sudden temperature change. It takes 10 seconds for transducer to reach equilibrium condition (five times time constant). The time taken to reach half of temperature difference will be |
| A. | 1.38 s |
| B. | 5 s |
| C. | 8.62 s |
| D. | 0.9 s |
| Answer» B. 5 s | |
| 120. |
A rectifier voltmeter using bridge rectifier and PMMC meter is calibrated to read rms value of sine wave. A triangular wave is applied to it and it reads 6.82 V. The rms value of triangular wave is |
| A. | about 6.5 V |
| B. | about 10 V |
| C. | below 500°C |
| D. | below 100°C |
| Answer» C. below 500¬∞C | |
| 121. |
An electrodynamometer instrument has the advantage of |
| A. | freedom from hysteresis and eddy currents because air cored coils are used |
| B. | freedom from hysteresis and eddy currents because cores of coils have special ferromagnetic material |
| C. | high torque/weight ratio |
| D. | low cost |
| Answer» B. freedom from hysteresis and eddy currents because cores of coils have special ferromagnetic material | |
| 122. |
In Weston frequency meter, the magnetic axes of the two fixed coils are |
| A. | inclined at 60° |
| B. | inclined at 15° |
| C. | Alternating voltage and current contain odd and even harmonics |
| D. | The inductance in a circuit reduces the effect of harmonics and makes current wave more sinusoidal than voltage wave |
| Answer» C. Alternating voltage and current contain odd and even harmonics | |
| 123. |
The dead zone in a pyrometer is 0.125% of span. The calibration is 400°C to 1000°C. What temperature change might occur before it is detected. |
| A. | 0.125°C |
| B. | 0.75°C |
| C. | 0.4°C |
| D. | 1°C |
| Answer» C. 0.4¬∞C | |
| 124. |
A moving iron voltmeter reads 250 V when connected to 250 V dc. If connected to 250 V 50 Hz, the voltmeter reading is likely to be |
| A. | 248 V |
| B. | 210 V |
| C. | 0.0025 |
| D. | 0.0035 |
| Answer» D. 0.0035 | |
| 125. |
To measure an unknown ac voltage by an ac potentiometer it is desirable that supply for the potentiometer is taken |
| A. | from a battery |
| B. | from a source which is not the same as unknown voltage |
| C. | from the same source as the unknown voltage |
| D. | either (a) or (b) |
| Answer» D. either (a) or (b) | |
| 126. |
Load cell uses |
| A. | mutual inductance |
| B. | strain gauge |
| C. | Both A and R are true and R is correct explanation of A |
| D. | Both A and R are true but R is not correct explanation of A |
| Answer» E. | |
| 127. |
An average responding rectifier type electronic voltmeter has its scale calibrated in terms of rms value of sine wave. If 100 V peak value square wave is fed to this voltmeter, the reading will be |
| A. | 111 V |
| B. | 100 V |
| C. | 90.9 V |
| D. | 70.7 V |
| Answer» B. 100 V | |
| 128. |
If Ey is the voltage applied to Y plates, the vertical deflection of beam is proportional to |
| 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» B. to connect a capacitor in parallel with coil | |
| 129. |
If the secondary winding of CT is opened when primary coil is carrying current |
| A. | transformer will burn immediately |
| B. | there will be weak flux density in core |
| C. | there will be very high induced voltage in secondary |
| D. | there will be high current in secondary |
| Answer» D. there will be high current in secondary | |
| 130. |
Panel instruments are generally mounted vertically. |
| 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 | |
| 131. |
Assertion (A): In two wattmeter method of 3 phase power measurement, one of the wattmeters would read negative if power factor of load is less than 0.5.Reason (R): In two wattmeter method of 3 phase power measurement, both the wattmeters would show equal readings if power factor of load is unity. |
| 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 | |
| 132. |
In figure, the reading of wattmeter will be proportional |
| A. | 3 VI sin θ |
| B. | V I sin θ |
| C. | 2, 3, 4 |
| D. | 1, 2, 3 |
| Answer» D. 1, 2, 3 | |
| 133. |
The coding system generally used in digital telemetry is |
| A. | PPM (Pulse position modulation) |
| B. | PAM (Pulse amplitude modulation) |
| C. | PCM (Pulse code modulation) |
| D. | PDM (Pulse duration modulation) |
| Answer» D. PDM (Pulse duration modulation) | |
| 134. |
The scale of hot wire ammeter is |
| A. | linear |
| B. | non-linear |
| C. | cramped |
| D. | absolute linear |
| Answer» C. cramped | |
| 135. |
The pointer of an indicating instrument should be |
| A. | very light |
| B. | very heavy |
| C. | neither heavy nor light |
| D. | heavy |
| Answer» B. very heavy | |
| 136. |
The wave applied to X plates, for ohtaining trace of voltage wave, is |
| A. | sawtooth wave |
| B. | sinusoidal wave |
| C. | rectangular wave |
| D. | either (a) or (c) |
| Answer» B. sinusoidal wave | |
| 137. |
Which of the following, is not a piezoelectric material? |
| A. | Rochelle salt |
| B. | Quartz |
| C. | Lithium sulphate |
| D. | Sodium bicarbonate |
| Answer» E. | |
| 138. |
DC ampere hour meter is an indicating instrument. |
| A. | 1 |
| B. | |
| C. | 1 |
| D. | |
| Answer» C. 1 | |
| 139. |
The device having highest photo sensitivity is |
| A. | photoconductive cell |
| B. | photovoltaic cell |
| C. | photodiode |
| D. | phototransistor |
| Answer» B. photovoltaic cell | |
| 140. |
Two numbers are 131 ± 5 and 629 ± 3. The sum of the numbers with range of doubt is |
| A. | 760 ± 8 |
| B. | 760 ± 2 |
| C. | 760 + 8 |
| D. | 760 - 8 |
| Answer» B. 760 ¬± 2 | |
| 141. |
The multiplier resistance and meter coil in a voltmeter are in |
| A. | series-parallel |
| B. | either (a) or (b) |
| C. | friction compensation |
| D. | creep compensation |
| Answer» B. either (a) or (b) | |
| 142. |
Assertion (A): If the reading of an instrument is low, the error is large.Reason (R): The error of an instrument is certain percentage of its full scale deflection. |
| 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 | |
| 143. |
In an Anderson bridge the unknown inductance is measured in terms of |
| A. | known inductance and resistance |
| B. | known inductance |
| C. | known capacitance and resistance |
| D. | known capacitance |
| Answer» D. known capacitance | |
| 144. |
While calibrating an ammeter by a dc potentiometer it is necessary to use a standard resistance. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 145. |
PCM employing 4 bit code is used to send data having frequency range from 0 to 2 kHz. The minimum required bandwidth of carrier channel is |
| A. | 2 kHz |
| B. | 4 kHz |
| C. | 8 kHz |
| D. | 16 kHz |
| Answer» C. 8 kHz | |
| 146. |
In a megger the controlling torque is provided by |
| A. | spring |
| B. | gravity |
| C. | coil |
| D. | eddy current |
| Answer» D. eddy current | |
| 147. |
A Weston frequency meter is |
| A. | moving coil instrument |
| B. | moving iron instrument |
| C. | dynamometer instrument |
| D. | induction instrument |
| Answer» C. dynamometer instrument | |
| 148. |
Assertion (A): Megger is used to check insulation resistance of cables. Reason (R): Insulation resistance of cables is very high. |
| 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 | |
| 149. |
Both X and Y plates of a CRO are excited by ac signals. The display is an ellipse which makes one rotation in 5 seconds. This means that |
| A. | the frequency of one input is 5 times that of other |
| B. | the difference between the frequencies of the two signals is one fifth of hertz |
| C. | the difference between the frequencies of the two signals is 5 Hz |
| D. | either (a) or (c) |
| Answer» C. the difference between the frequencies of the two signals is 5 Hz | |
| 150. |
It is required to measure the true open circuit emf of a battery. The best device is |
| A. | dc voltmeter |
| B. | ammeter and known resistance |
| C. | dc potentiometer |
| D. | either (a) or (c) |
| Answer» D. either (a) or (c) | |