# Electrical Measurements & Units Test Questions - 4

1)   Electrodynamic instruments can be used as

a. Ammeter
b. Voltmeter
c. Wattmeter
d. All of these
 Answer  Explanation  Related Ques ANSWER: All of these Explanation: No explanation is available for this question!

2)   The equivalent inductance of fixed coil and moving coil of electrodynamic instrument is given by

a. L1 + L2 + 2M
b. L1 + L2 - 2M
c. L1 + L2 + M
d. L1 + L2 - M
 Answer  Explanation  Related Ques ANSWER: L1 + L2 + 2M Explanation: No explanation is available for this question!

3)   The scale of electrodynamic instrument when it is used as ammeter and when it is used as voltmeter is

a. Uniform, uniform
b. Crowded near zero, crowded near zero
c. Cramped near zero, cramped in the middle
d. Uniform, cramped near zero
 Answer  Explanation  Related Ques ANSWER: Crowded near zero, crowded near zero Explanation: No explanation is available for this question!

4)   In an electrodynamic instrument, the number of control springs present is / are

a. Two
b. One
c. Four
d. Zero
 Answer  Explanation  Related Ques ANSWER: Two Explanation: No explanation is available for this question!

5)   A electrodynamic ammeter has current flowing through it of 20 A and torsional constant of controlling spring of 10-6 N-m/degree. If the mutual inductance changes uniformly at the rate of 0.0025 μH/degree, then its angular deflection for full scale is

a. 43.68 degree
b. 57.29 degree
c. 68.32 degree
d. 69.69 degree
 Answer  Explanation  Related Ques ANSWER: 57.29 degree Explanation: No explanation is available for this question!

6)   For a dynamometer wattmeter, the variation of inductance with angular position of moving system is 0.06 mH/radian and spring constant is 10 X 10-6 N-m/radian. The current flowing in the instrument is 8 A. If the full scale deflection is 76 degree, then the current required in the voltage coil at full scale on d.c. circuit is

a. 27.6 μA
b. 29.89 μA
c. 35.3 μA
d. 37.28 μA
 Answer  Explanation  Related Ques ANSWER: 27.6 μA Explanation: No explanation is available for this question!

7)   The deflection angle in hot wire instruments is

a. Directly proportional to the current
b. Directly proportional to the square of current
c. Inversely proportional to the current
d. Inversely proportional to the square of current
 Answer  Explanation  Related Ques ANSWER: Directly proportional to the square of current Explanation: No explanation is available for this question!

8)   Hot-wire instruments are suitable for

a. AC work only
b. DC work only
c. Both AC and DC work
d. None of these
 Answer  Explanation  Related Ques ANSWER: Both AC and DC work Explanation: No explanation is available for this question!

9)   The current sensitive instruments are

a. PMMC
b. Hot wire instruments
c. Electrostatic instruments
d. Both (a) and (b)
 Answer  Explanation  Related Ques ANSWER: Both (a) and (b) Explanation: No explanation is available for this question!

10)   Power consumption in permanent magnet moving coil instrument and hot-wire instruments are

a. Low, low
b. Low, high
c. High, low
d. High, high
 Answer  Explanation  Related Ques ANSWER: Low, high Explanation: No explanation is available for this question!

11)   In the given frequency range, which type of instrument will have highest accuracy

a. electrodynamometer
b. hot-wire instrument
c. electrostatic instrument
d. PMMC
 Answer  Explanation  Related Ques ANSWER: electrodynamometer Explanation: No explanation is available for this question!

12)   Megger is a portable instrument. It is used for the measurement of

a. Low inductance
b. Low resistance
c. High inductance
d. High resistance
 Answer  Explanation  Related Ques ANSWER: High resistance Explanation: No explanation is available for this question!

13)   In a portable instrument, the effect of stray magnetic field on actuating torque will be maximum when the operating field and stray fields are

a. Parallel to each other
b. Perpendicular to each other
c. Inclined at 45 degree
d. Opposite to each other
 Answer  Explanation  Related Ques ANSWER: Parallel to each other Explanation: No explanation is available for this question!

14)   The thermocouple instruments works on the principle of Seebeck effect. The amount of heat produced is

a. Directly proportional to the current
b. Directly proportional to the square of current
c. Inversely proportional to the current
d. Inversely proportional to the square of current
 Answer  Explanation  Related Ques ANSWER: Directly proportional to the square of current Explanation: No explanation is available for this question!

15)   The thermocouple ammeter scale is

a. Linear
b. Cramped at low end and open at high end
c. Open at low end and cramped at high end
d. Cramped at the middle
 Answer  Explanation  Related Ques ANSWER: Cramped at low end and open at high end Explanation: No explanation is available for this question!

16)   The heater wire of thermocouple instruments are made of smaller area of cross section to

a. reduce the skin effect
b. reduce temperature error
c. reduce frequency error
d. increase inductance
 Answer  Explanation  Related Ques ANSWER: reduce the skin effect Explanation: No explanation is available for this question!

17)   Induction type instruments are generally used as

a. Ammeter
b. Voltmeter
c. Wattmeter
d. All of these
 Answer  Explanation  Related Ques ANSWER: All of these Explanation: No explanation is available for this question!

18)   A cylindrical type with split phase winding induction ammeters employs

a. A rotating disc
b. A hollow aluminium drum
c. A single flux producing winding
d. None of these
 Answer  Explanation  Related Ques ANSWER: A hollow aluminium drum Explanation: No explanation is available for this question!

19)   In induction voltmeter, split phase windings are obtained by connecting a

a. High resistances in series with windings of both the magnets
b. High resistance in series with the winding of one magnet and an inductive coil in series with the windings of other magnet
c. An inductive coil in series with the winding of one magnet and a capacitance in series with the windings of other magnet
d. Inductive coils in series with the winding of both the magnets
 Answer  Explanation  Related Ques ANSWER: High resistance in series with the winding of one magnet and an inductive coil in series with the windings of other magnet Explanation: No explanation is available for this question!

20)   For reducing the errors in an induction instrument the alternating current to be measured has

a. Same frequency with which the instrument was calibrated
b. High frequency compared with which the instrument was calibrated
c. Low frequency compared with which the instrument was calibrated
d. None of these
 Answer  Explanation  Related Ques ANSWER: Same frequency with which the instrument was calibrated Explanation: No explanation is available for this question!

21)   The frequency errors in induction instruments can be compensated by the use of

a. Non inductive shunt in both ammeters and voltmeters
b. Non inductive shunt in case of ammeters and are generally self compensated in case of voltmeters
c. Self compensated in case of both ammeters and voltmeters
d. Self compensated in case of ammeters and non inductive shunt in case of voltmeters
 Answer  Explanation  Related Ques ANSWER: Non inductive shunt in case of ammeters and are generally self compensated in case of voltmeters Explanation: No explanation is available for this question!

22)   The temperature errors in induction instruments can be compensated by

a. Hunting in both ammeters and voltmeters
b. Combination of shunt and swamping resistance in both ammeters and voltmeters
c. Hunting in case of ammeters and Combination of shunt and swamping resistance in case of voltmeters
d. Combination of shunt and swamping resistance in case of ammeters and hunting in case of voltmeters
 Answer  Explanation  Related Ques ANSWER: Hunting in case of ammeters and Combination of shunt and swamping resistance in case of voltmeters Explanation: No explanation is available for this question!

23)   Which among the following is not true about the induction instruments?

a. It can be used for ac measurements only
b. Damping is very efficient in case of induction instruments
c. Compensation for frequency temperature is not required
d. Cost is relatively high
 Answer  Explanation  Related Ques ANSWER: Compensation for frequency temperature is not required Explanation: No explanation is available for this question!

24)   In a moving coil of a meter swamping resistance is added to

a. Reduce the frequency error
b. Reduce the temperature error
c. Reduce the power consumption
d. All of these
 Answer  Explanation  Related Ques ANSWER: Reduce the temperature error Explanation: No explanation is available for this question!

25)   Swamping resistance is a resistance made up of

a. Alloy of manganin and copper
b. Alloy of aluminium and copper
c. Alloy of nickel and cobalt
d. Alloy of manganin and aluminium
 Answer  Explanation  Related Ques ANSWER: Alloy of manganin and copper Explanation: No explanation is available for this question!

26)   Electrostatic instruments are generally used as

a. Voltmeters
b. Ammeters
c. Wattmeters
d. Watt-hour meters
 Answer  Explanation  Related Ques ANSWER: Voltmeters Explanation: No explanation is available for this question!

27)   In electrostatic voltmeters, the principle of their operation is the force of attraction between electric charges on neighboring plates between which potential difference is maintained. The attracted-disc type electrostatic instruments are used for the measurement of

a. Very low voltages
b. Low voltages
c. High voltages
d. Very high voltages
 Answer  Explanation  Related Ques ANSWER: Very high voltages Explanation: No explanation is available for this question!

28)   A Kelvin’s multicellular voltmeter has a torsion head and a coach spring for

a. Protection against accidental fraction of suspension due to vibration
c. Torsion head for zero adjustment and coach spring for protection against accidental fraction of suspension due to vibration
d. Torsion head for protection against accidental fraction of suspension due to vibration and coach spring for zero adjustment
 Answer  Explanation  Related Ques ANSWER: Torsion head for zero adjustment and coach spring for protection against accidental fraction of suspension due to vibration Explanation: No explanation is available for this question!

29)   Electrostatic voltmeter instruments are suitable for

a. Ac work only
b. Dc work only
c. Both ac and dc work
d. None of these
 Answer  Explanation  Related Ques ANSWER: Both ac and dc work Explanation: No explanation is available for this question!

30)   If an electrostatic voltmeter is used on AC circuit and has non uniform waves, then it will read

a. Average values
b. RMS values
c. Peak values
d. All of these
 Answer  Explanation  Related Ques ANSWER: RMS values Explanation: No explanation is available for this question!

31)   In electrostatic instruments iron is not used in their construction. These instruments are

a. Free from hysteresis and eddy current losses
b. Free from temperature errors
c. Dependent on temperature errors
d. Both (a) and (b)
 Answer  Explanation  Related Ques ANSWER: Both (a) and (b) Explanation: No explanation is available for this question!

32)   The multiplying factor of electrostatic voltmeters is given by

a. (C + Cv) / C
b. (C + Cv) / Cv
c. C / (C+Cv)
d. Cv / (C+ Cv)
 Answer  Explanation  Related Ques ANSWER: (C + Cv) / C Explanation: No explanation is available for this question!

33)   The range of electrostatic voltmeter can be extended by using

a. Resistance potential divider method
b. Capacitance potential divider method
c. Both (a) and (b)
d. None of these
 Answer  Explanation  Related Ques ANSWER: Both (a) and (b) Explanation: No explanation is available for this question!

34)   The resistance potential divider method and capacitance potential divider method is used for

a. Both AC and DC
b. Former method can be used for both AC and DC and the later method can be used only for AC
c. Former method can be used for AC only and the later method can be used for both AC and DC
d. Former method can be used for DC only and the later method can be used only for AC
 Answer  Explanation  Related Ques ANSWER: Former method can be used for both AC and DC and the later method can be used only for AC Explanation: No explanation is available for this question!

35)   The indicating instruments with linear scale is

a. PMMC
b. Electrostatic instrument
c. Dynamometer instrument
d. Thermocouple instrument
 Answer  Explanation  Related Ques ANSWER: PMMC Explanation: No explanation is available for this question!

36)   In the given options, the secondary fundamental unit is

a. Length
b. Luminous intensity
c. Plane angle
d. Time
 Answer  Explanation  Related Ques ANSWER: Luminous intensity Explanation: No explanation is available for this question!

37)   Plane angle and solid angle are

a. Primary fundamental units
b. Secondary fundamental units
c. Supplementary units
d. Derived units
 Answer  Explanation  Related Ques ANSWER: Supplementary units Explanation: No explanation is available for this question!

38)   The unit of luminance is

a. Lumen
b. Candela per square meter
c. Lux
d. Lumen per square meter
 Answer  Explanation  Related Ques ANSWER: Candela per square meter Explanation: No explanation is available for this question!

39)   In electrostatic system of units, the unit of resistance is given by

a.-1L-1T]
b.-2L-1T-1]
c.-1L-1T-2]
d.-1L-2T]
 Answer  Explanation  Related Ques ANSWER: [ε-1L-1T] Explanation: No explanation is available for this question!

40)   If V0 is the velocity of light, μ0 is the permeability of free space and ε0 is the permittivity of free space, Then the equation for velocity in terms of permittivity and permeability is given by

a. V0 = 1/√(μ0ε0)
b. V0 = √(μ0ε0)
c. V0 = μ0ε0
d. V0 = 1/(μ0ε0)
 Answer  Explanation  Related Ques ANSWER: V0 = 1/√(μ0ε0) Explanation: No explanation is available for this question!