NTPC Exam Questions asked on Electrical and Electronic Measurements
The deflection depends on the average value in
(a) Moving-iron meter
(b) Rectifier meter
(c) Hot-wire meter
(d) Moving-coil meter
Some wire-wound resistors have bilfilar winding. This type of winding is used to
(a) increase the thermal stability
(b) reduce the tolerance
(c) reduce the inductance of winding
(d) double the power rating of the resistors
The secondary winding of a current transformer is open when current is flowing in the primary. Then,
(a) there will be high current in primary
(b) there will be very high secondary voltage
(c) the transformer will burn out immediately
(d) the meter will burn out
Consider the following statements regarding an electromagnetic flowmeter –
(1) A.C. excitation is used to avoid polarisation of the fluid
(2) The meter calibration is changed as the viscosity of the fluid changes.
(3) Stainless stell pipes can be used for measuring the flow of fluids of high conductivity
Of these statements,
(a) 1, 2 and 3 are correct
(b) 1 and 2 are correct
(c) 2 and 3 are correct
(d) 1 and 3 are correct
Schering bridge is used to
(a) determine dielectric loss
(b) determine the inductance
(c) measure low resistance
(d) measure mutual inductance
Which of the following instruments can be used for measurement of alternating current only?
(a) Permanent magnet type ammeter
(b) Induction type ammeter
(c) Moving-iron voltmeter
(d) Moving-iron ammeter
A milliammeter can be used as
(a) voltmeter and ammeter
(b) wattmeter
(c) ohmmeter
(d) frequency meter
In series LCR circuit, at reasonance
(a) current is maximum, power factor is zero
(b) current is maximum, power factor is unity
(c) current is maximum, power factor is unity
(d) None of these
A network is said to be non-linear if it does not satisfy
(a) super position condition
(b) homogeneity condition
(c) both (a) and (b)
(d) associative condition
Which of the following is an active element of a circuit?
(a) Resistance
(b) Inductance
(c) Ideal current source
(d) Capacitance
Which of the following theorems enables a number of voltage (or current) source to be combined directly into a single voltage (or current) source?
(a) Compensation theorem
(b) Reciprocity theorem
(c) Superposition theorem
(d) Millaman’s theorem
A thermal protection switch is able to protect against
(a) over load
(b) over voltage
(c) temperature
(d) short circuit
Resistance switching is used in
(a) bulkoil circuit breakers
(b) minimum oil circuit breakers
(c) air-blas circuit breakers
(d) all types of breakers
Earthing is necessary to give protection against
(a) Voltage fluctuation
(b) Overloading
(c) danger of electric shock
(d) high temperature of the conductors
The highest voltage gain can be obtained from a
(c) CC
(b) CE
(c) CB
(d) both CE and CB
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