Q151. The accuracy of digital voltmeters is usually:
A) ±0.01%
B) ±0.1%
C) ±1%
D) ±5%
Ans: B
Q152. A dynamometer wattmeter can be used for:
A) DC only
B) AC only
C) Both AC and DC
D) High frequency only
Ans: C
Q153. In PMMC instrument, the deflecting torque is produced by:
A) Magnetic field
B) Current through coil
C) Interaction of fields
D) Voltage applied
Ans: C
Q154. Hot-wire instruments are mainly used for:
A) Low current DC
B) High frequency AC
C) Energy measurement
D) Resistance measurement
Ans: B
Q155. The bridge suitable for measurement of inductance at power frequencies is:
A) Maxwell bridge
B) Hay’s bridge
C) Anderson’s bridge
D) Schering bridge
Ans: A
Q156. The primary function of a CT is to:
A) Step down current
B) Step up current
C) Step up voltage
D) Measure resistance
Ans: A
Q157. A CT should always be operated with:
A) Open secondary
B) Shorted secondary
C) High resistance load
D) Low resistance shunt
Ans: B
Q158. Which type of galvanometer is used in potentiometers?
A) Ballistic
B) Vibration
C) Sensitive D’Arsonval type
D) Hot wire
Ans: C
Q159. In a CRO, triggering circuit is used to:
A) Stabilize waveform
B) Control intensity
C) Increase frequency
D) Reduce distortion
Ans: A
Q160. A digital storage oscilloscope (DSO) stores signals in:
A) Capacitors
B) Digital memory
C) Magnetic core
D) Analog filters
Ans: B
Q161. Deflection sensitivity of a CRO is expressed in:
A) mm/V
B) V/mm
C) dB
D) W/m
Ans: A
Q162. Which instrument works on principle of “deflection proportional to square of current”?
A) MI
B) PMMC
C) CRO
D) Wattmeter
Ans: A
Q163. In AC bridges, balance condition is independent of:
A) Frequency
B) Voltage
C) Current
D) Power
Ans: B
Q164. Megger works on:
A) Induction principle
B) Electrodynamometer principle
C) Heating effect
D) Magnetic repulsion
Ans: B
Q165. A 0.5 accuracy class instrument means error is within:
A) ±0.05%
B) ±0.5%
C) ±5%
D) ±1%
Ans: B
Q166. Digital frequency meters count:
A) Amplitude of signal
B) Pulses per second
C) Voltage peaks
D) Phase difference
Ans: B
Q167. The voltmeter that consumes least power is:
A) PMMC
B) MI
C) Electrostatic
D) Digital
Ans: C
Q168. The speed of disc in an energy meter is proportional to:
A) Voltage
B) Current
C) Power
D) Energy
Ans: C
Q169. The braking torque in induction type energy meter is proportional to:
A) Eddy current
B) Speed of disc
C) Flux density
D) Both B & C
Ans: D
Q170. Which instrument cannot measure true RMS?
A) Hot-wire
B) Thermocouple
C) MI
D) PMMC
Ans: D
Q171. Digital instruments suffer mainly from:
A) Parallax error
B) Quantization error
C) Hysteresis error
D) Temperature drift
Ans: B
Q172. Analog instruments have the advantage of:
A) High speed
B) Easy storage
C) Trend observation
D) No parallax error
Ans: C
Q173. Which method is most suitable for testing energy meters?
A) Phantom loading
B) Actual loading
C) Resistance method
D) Bridge method
Ans: A
Q174. A CRO time base provides:
A) Sinusoidal sweep
B) Linear sawtooth sweep
C) Exponential sweep
D) Rectangular sweep
Ans: B
Q175. Oscillograph is another name for:
A) Wattmeter
B) Voltmeter
C) CRO
D) Galvanometer
Ans: C
Q176. Which meter is used for earth resistance measurement?
A) Wattmeter
B) Megger
C) Earth tester
D) Energy meter
Ans: C
Q177. A bolometer is used for measurement of:
A) High frequency power
B) Voltage
C) Resistance
D) Low frequency current
Ans: A
Q178. An average responding rectifier type voltmeter is calibrated in terms of:
A) Peak value
B) RMS value
C) Average value
D) Instantaneous value
Ans: B
Q179. A thermocouple instrument measures:
A) Peak value
B) Average value
C) RMS value
D) None
Ans: C
Q180. The Q-meter is used for:
A) Power measurement
B) Quality factor of coils
C) Energy measurement
D) Phase measurement
Ans: B
Q181. In CRO, the horizontal plates are used for:
A) Vertical deflection
B) Horizontal deflection
C) Focusing
D) Intensity control
Ans: B
Q182. The vertical deflection in CRO is proportional to:
A) Input current
B) Input voltage
C) Frequency
D) Resistance
Ans: B
Q183. The device used to measure instantaneous voltage waveform is:
A) DMM
B) CRO
C) Energy meter
D) Ammeter
Ans: B
Q184. Sensitivity of a galvanometer is increased by:
A) Decreasing coil turns
B) Increasing magnet strength
C) Increasing spring constant
D) Using thick wire
Ans: B
Q185. Induction type instruments cannot work on DC because:
A) Eddy currents are not produced
B) Heating is absent
C) Scale is non-uniform
D) Flux is zero
Ans: A
Q186. The ratio error of CT is caused by:
A) Leakage flux
B) Excitation current
C) Winding resistance
D) All of the above
Ans: D
Q187. The phase angle error of CT is due to:
A) Magnetizing current
B) Leakage reactance
C) Burden
D) All of the above
Ans: D
Q188. Instrument transformers are used for:
A) Extending range
B) Providing isolation
C) Protection
D) All of the above
Ans: D
Q189. In digital voltmeters, the reference used is:
A) Analog
B) DC voltage standard
C) Resistance standard
D) Current standard
Ans: B
Q190. A frequency counter works on:
A) Time period measurement
B) Pulse counting
C) Phase difference
D) RMS detection
Ans: B
Q191. A phasor diagram can be obtained using:
A) CRO
B) Wattmeter
C) Energy meter
D) Potentiometer
Ans: A
Q192. Integrating instruments register:
A) Energy
B) Voltage
C) Current
D) Resistance
Ans: A
Q193. An oscilloscope probe increases:
A) Input capacitance
B) Input resistance
C) Frequency range
D) Both B & C
Ans: D
Q194. The sensitivity of potentiometer is defined as:
A) Volts per unit length
B) Current per unit length
C) Ohms per unit length
D) None
Ans: A
Q195. A digital wattmeter displays:
A) Average power
B) True power
C) Apparent power
D) Both active and reactive power
Ans: B
Q196. AC ammeter is usually of:
A) PMMC type
B) MI type
C) Hot wire type
D) Digital type
Ans: B
Q197. Which device is used to test polarity of supply?
A) CRO
B) Tester (neon lamp)
C) Megger
D) Potentiometer
Ans: B
Q198. A bridge which is frequency sensitive is:
A) Wien’s bridge
B) Maxwell’s bridge
C) Kelvin bridge
D) Schering bridge
Ans: A
Q199. The standard for frequency is maintained using:
A) Quartz crystal oscillator
B) Induction motor
C) Synchronous motor
D) Potentiometer
Ans: A
Q200. The least count of digital instrument depends on:
A) Resolution
B) Accuracy
C) Scale length
D) Pointer deflection
Ans: A
Q201. Moving coil galvanometer is:
A) Electrodynamic type
B) Permanent magnet type
C) Electrostatic type
D) Induction type
Ans: B
Q202. Which type of instrument is most suitable for DC only?
A) PMMC
B) MI
C) Thermocouple
D) Hot wire
Ans: A
Q203. In CRO, focusing of electron beam is achieved by:
A) Magnetic field
B) Electrostatic lens
C) Grid bias
D) Anode voltage
Ans: B
Q204. A true RMS meter is required to measure:
A) Sine wave
B) Distorted waveforms
C) DC
D) None
Ans: B
Q205. The resistance of a shunt should be:
A) Very high
B) Very low
C) Equal to coil resistance
D) Infinite
Ans: B
Q206. In dynamometer wattmeter, deflection is proportional to:
A) VI cosφ
B) VI sinφ
C) VI
D) V²
Ans: A
Q207. The instrument used to check synchronism is:
A) Wattmeter
B) Synchroscope
C) CRO
D) Var meter
Ans: B
Q208. A vibration galvanometer responds to:
A) DC
B) AC of small frequency band
C) High frequency AC
D) Voltage only
Ans: B
Q209. AC energy meters are generally of:
A) Induction type
B) Electrostatic type
C) PMMC type
D) MI type
Ans: A
Q210. An integrating instrument integrates with respect to:
A) Current
B) Time
C) Voltage
D) Frequency
Ans: B
Q211. D’Arsonval galvanometer works on:
A) Magnetic effect
B) Electrostatic effect
C) Heating effect
D) Induction effect
Ans: A
Q212. Digital multimeters are free from:
A) Loading effect
B) Quantization error
C) Temperature drift
D) Parallax error
Ans: D
Q213. For best accuracy, potentiometer wire should have:
A) High resistivity
B) Low resistivity & uniform cross-section
C) Magnetic property
D) Large diameter
Ans: B
Q214. AC bridges use:
A) Null detection method
B) Deflection method
C) Integration method
D) Resonance method
Ans: A
Q215. Which is most suitable for audio frequency range measurement?
A) Wien’s bridge
B) Maxwell bridge
C) Schering bridge
D) Hay’s bridge
Ans: A
Q216. CRO intensity control changes:
A) Grid bias
B) Plate voltage
C) Sweep frequency
D) Trigger level
Ans: A
Q217. A dielectric loss angle is also called:
A) Power factor angle
B) Dissipation factor
C) Phase angle
D) Both A & B
Ans: D
Q218. In power measurement, phantom loading avoids:
A) Heating loss
B) Energy wastage
C) Overloading of supply
D) All of the above
Ans: D
Q219. A synchroscope’s slow movement indicates:
A) Large frequency difference
B) Small frequency difference
C) Voltage mismatch
D) Phase shift error
Ans: B
Q220. Which bridge uses a Wagner earthing device?
A) AC bridge
B) DC bridge
C) Kelvin bridge
D) Schering bridge
Ans: A
Q221. The inductance is measured in:
A) Ohms
B) Henry
C) Weber
D) Tesla
Ans: B
Q222. CRO deflection factor is reciprocal of:
A) Sensitivity
B) Gain
C) Resistance
D) Frequency
Ans: A
Q223. A 3-phase power can be measured by:
A) One wattmeter method
B) Two wattmeter method
C) Three wattmeter method
D) All of the above
Ans: D
Q224. A digital counter is used for:
A) Voltage measurement
B) Frequency measurement
C) Current measurement
D) Resistance measurement
Ans: B
Q225. Instrument transformers improve:
A) Accuracy
B) Range
C) Safety
D) All of the above
Ans: D
Q226. The bridge suitable for measuring high Q inductors:
A) Hay’s bridge
B) Maxwell bridge
C) Anderson bridge
D) Wien bridge
Ans: A
Q227. The bridge suitable for low Q inductors:
A) Hay’s bridge
B) Maxwell bridge
C) Anderson bridge
D) Wien bridge
Ans: B
Q228. A piezoelectric crystal is used for:
A) Voltage measurement
B) Frequency standard
C) Current measurement
D) Resistance measurement
Ans: B
Q229. The oscilloscope axis X represents:
A) Time
B) Voltage
C) Current
D) Frequency
Ans: A
Q230. The oscilloscope axis Y represents:
A) Time
B) Voltage
C) Current
D) Resistance
Ans: B
Q231. The unit of capacitance is:
A) Henry
B) Coulomb
C) Farad
D) Siemens
Ans: C
Q232. The unit of reluctance is:
A) Henry
B) Ampere-turns per Weber
C) Ohm
D) Tesla
Ans: B
Q233. The main source of error in MI instrument is:
A) Hysteresis
B) Temperature
C) Eddy current
D) All of the above
Ans: D
Q234. In digital instruments, resolution is determined by:
A) Number of display digits
B) Accuracy class
C) Reference voltage
D) Sampling rate
Ans: A
Q235. A CRO measures phase difference using:
A) Dual trace method
B) Lissajous figures
C) Sweep frequency
D) Time base
Ans: B
Q236. A bolometer works on:
A) Change in resistance with temperature
B) Change in capacitance
C) Change in inductance
D) Magnetic effect
Ans: A
Q237. A digital tachometer measures:
A) Voltage
B) Speed
C) Resistance
D) Frequency
Ans: B
Q238. The working principle of electrostatic voltmeter is:
A) Force between charges
B) Induction
C) Heating effect
D) Eddy current
Ans: A
Q239. Deflection sensitivity in CRO depends on:
A) Length of plates
B) Voltage applied
C) Distance between plates
D) All of the above
Ans: D
Q240. The function of trigger in CRO is:
A) Synchronization
B) Deflection
C) Sweep control
D) Focusing
Ans: A
Q241. PMMC meters can measure:
A) DC only
B) AC only
C) Both AC and DC
D) Reactive power
Ans: A
Q242. The maximum torque in MI instrument is obtained when pointer deflection is:
A) 0°
B) 45°
C) 90°
D) 180°
Ans: B
Q243. The power consumed in a voltmeter is called:
A) Loss
B) Power factor
C) Volt-ampere loss
D) Burden
Ans: D
Q244. CT secondary resistance is called:
A) Burden
B) Resistance
C) Impedance
D) Shunt
Ans: A
Q245. The instrument with least power consumption is:
A) Electrostatic
B) Digital
C) PMMC
D) Hot wire
Ans: A
Q246. A potentiometer can measure:
A) Unknown emf
B) Internal resistance
C) Small voltage difference
D) All of the above
Ans: D
Q247. A galvanometer is converted to voltmeter by:
A) Shunt
B) Multiplier
C) Both A & B
D) Series resistance
Ans: B
Q248. A galvanometer is converted to ammeter by:
A) Shunt resistance
B) Series resistance
C) Multiplier
D) Inductor
Ans: A
Q249. A DC potentiometer is used for:
A) Measuring emf
B) Measuring current
C) Measuring resistance
D) Measuring power
Ans: A
Q250. The AC potentiometer can measure:
A) Magnitude only
B) Phase only
C) Both magnitude and phase
D) None
Ans: C
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