The Req for the circuit shown in figure is
Length of the cable is doubled, its capacitance C will be
Swamping resistance is used to compensate
Unit of deflection sensitivity of a CRO is
The units of deflection sensitivity of the CRO is – meter per volt.
CRO stands for Cathode Ray Oscilloscope. It is an electronic device with the CRT as its main component and other associated circuits. The CRO has horizontal and vertical plates in between the electron gun and the screen in order to deflect the beam according to the input signal.
The deflection sensitivity of a CRO is defined as the vertical deflection of the beam on the screen per unit deflecting voltage.
It is also defined as the deflection produced per volt of deflecting voltage. Therefore, the units of deflection sensitivity of the CRO is – meter per volt (m⋅V−1).
Relative permittivity can be measured by
A three phase 440V, 6 pole, 50Hz squirrel cage induction motor is running at a slip of 5%.The speed of stator magnetic field with respect to rotor magnetic field and speed of rotor w.r.t.stator magnetic field are
N_{s} = (120 × f)/P
= (120 × 50)/6
= 1000 rpm
Rotor speed = N_{s} – SN_{s} = 950 r.p.m.
Stator magnetic field speed, N_{s} = 1000 r.p.m.
Rotor magnetic field speed, N_{s} = 1000 r.p.m.
Relative speed between stator and rotor magnetic fields is zero
Rotor speed with respect to stator magnetic field = 950 – 1000 = – 50 r.p.m.
Oxide film arrester has which of the following properties ?
What is the name of the fluorescent material that gives red colour fluorescence ?
The BH curve for.......will be straight line passing through the origin.
The essential condition for parallel operation of two D.C. generators is that they have
Plug setting of a relay can be altered by varying
If the fault current is 2000 A, the relay setting is 50% and CT ratio is 400:5, then plug settingmultiplier will be
In a Dconnected source feeding a Yconnected load
Which of the following loads normally needs starting torque more than rated torque ?
Which of the following transistor configuration circuit is much less temperature dependent ?
The collector characteristics of a common emitter connected thyristor may be used to findits
A zener voltage regulator has load requirement of 12V and 2A. The zener diode minimumcurrent requirement is 0.2A. The minimum voltage at input is 24V. What is the seriesresistance with source required ?
A constant load power means a uniform conversion of
To tune a parallel resonant circuit to a higher frequency, the capacitance should be
The effect of inserting a resistance in series with the field winding of a shunt motor is to
When using ohmmeter, applied voltage is to be disconnected from the circuit because
For the circuit shown in figure, the voltage across the capacitor during steady statecondition is
For high accuracy the meter has
A 10 MHz CRO has
Semi conductor diode time constant is equal to
Consider the circuit in the below figure. What is the power delivered by the 24V source ?
For a given torque, reducing the diverterresistance of a d.c. series motor
A 20 kVA, 2000/200 V, 1f transformer has name plate leakage impedance of 8%. Voltagerequired to be applied on the high voltage side to circulate full load current with the low voltagewinding shortcircuited will be
A 100 km long transmission line is loaded at 110 kV. If the loss of line is 15 MW and theload is 150 MVA, the resistance of the line is
Corona loss increases with
In case line to line fault occurs, the short circuit current of an alternator will depend on its
An overhead transmission line has a span of 220 metres the conductor waiting 0.604 kg/m. What will be the maximum sag if the working tension is 2879 kg.
(Maximum sag ) S = ωL2 / 8T
Where ,
ω – weight of conductor per meter
L – span
T – Working tension
Therefore, S = (0.604 × 2202) / (8 × 2879) = 1.269 m ~ 1.27 m.
Find RAB for the circuit shown in figure.
If the voltage V across 10W resistance is 10 V, what is the voltage E of the voltage sourcein the circuit shown below ?
Integrating principle in the digital measurement is the conversion of
Delta/star transformer works satisfactorily when
Negative voltage regulation is indicative that the load is
Iron loss of a transformer can be measured by
In the circuit shown below, what is the value of the current I ?
The transformation ratio of an induction motor can be found by
The armature reaction of an alternator will be completely magnetizing when load power factoris
In the network shown below, it is given that V = 1V and dt /dv = – 10 v/s at a time t, wheret is the time after the switch s is closed what is the value of C ?
The resistance seen from the terminal A and B of the device whose characteristics is shown in
the figure below is
Regarding skewing of motor bars in a squirrel cage induction motor (SCIM) which statementis false ?
If the input to the prime mover of an alternator (in a system of three alternators) is kept
constant and the excitation is changed, the
The coupling angle or load angle of a synchronous motor is defined as the anglebetween the
Most commonly employed trivalent impurities are
Ripple factor of a full wave rectifier without filter will be
Configuration used to connect high impedance source to a low impedance load is
The minimum value that the characteristic impedance of an air dielectric parallel wire linecan have is
In an Ntype semiconductor, the concentration of minority carriers mainly depends upon
A current of 5mA flows in a resistanceless choke from a 200V alternating source. Theenergy consumed in the choke is
The current drawn by a tungsten filament lamp is measured by an ammeter. The ammeter reading under steady state condition will be ____ the ammeter reading when the supply is switched on
When a filament lamp is cold(when supply is switched off), it behaves differently than when it’s at its normal operating temperature. The resistance of the filament of the bulb increases with increase in temperature. Hence when it glows its resistances is greater than when it is cold. and in the process the lamp current changes. In the case of a cold incandescent lamp (a filament lamp), the inrush current peaks at approximately ten times the steadystate operating current, but it lasts a relatively short duration, no more than a few cycles.
Therefore the ammeter reading under the steadystate condition is less than then ammeter reading when the supply is switched on.
Two sinusoidal currents are given by the equations , The phase difference between them is degrees.
The most economic load on an overhead line is
The stability of an arc in vacuum depends upon the
The combination of HRC fuse and circuit breaker is used, the circuit breaker operatesfor
A distance relay measures
In an A.C. circuit, the ratio of KW/KVA represents
When the supply voltage to an induction motor is reduced by 10%, the maximum torque willdecrease by
In the figure the inductance of coil 1 is
In the analysis of transistor circuit we usually use
Two identical heaters each marked 2000 W, 250 V are placed in series and then connectedto 250 volt supply, their combined rate of heating is
∴ P = V^{2}/R ⇒ R = V^{2}/P
∴ Each heater resistance
R = (250)^{2}/2000 = R = 125/4Ω
Since heaters are connected in series so their resistance will be connected in parallel so total resistance
1/R_{T }= 1/R + 1/R = 4/125 + 4/125
⇒ R_{T} = 125/8 Ω
In three phase, power measurement, the power factor of the load will be
Usually a C.T. has
The material of the shunt should have ____ temperature coefficient of resistance
If the current through the operating coil of a moving iron instrument is doubled, the operatingforce becomes
168. In the following circuit, what will be the total capacitance
Two things which are the same for primary and secondary of transformers are
Short pitched coils in the alternators are used to
A magnetic circuit has a m.m.f. of 400 AT and a reluctance of 2 × 105 AT/Wb. The magneticflux in the magnetic circuit is
For the purpose of plugging
Candela is the unit of
Which torque is greater
A 30 kW, 300 V dc shunt generator has armature and field resistance 0.05W and 100Wrespectively. What is the generated emf ?
The circuit comprises of a coil of resistance R and inductance L, in parallel with an ideal
capacitor C. At the resonant frequency, the impedance of the parallel combination is
Low resistance from few ohms down to one micro ohm is measured using which one of thefollowing instruments ?
Which one of the following multirange voltmeter has high and constant input impedance ?
A moving coil instrument gives full scale deflection for 1 mA and has a resistance of5W. If a resistance of 0.55W is connected in parallel to the instrument, what is the maximum value of current it can measure ?
When two wattmeter method of measurement of power is used to measure power in abalanced 3f circuit, if one wattmeter reading is zero, then
The illumination is directly proportional to the cosine of the angle made by the normal to theilluminated surface with the direction of the incident flux. Above statement is associated with
Optical instruments used for the comparison of candle power of different sources are knownas
The capacitor used in the auto transformer circuit for sodium vapour lamps, is for
Arc blow is a welding defect which is encountered in
Which method would you recommend for welding of aluminium alloys ?
When d is the dielectric loss angle, the value of tan d increases with
Which component of the no load current of the transformer is opposite in phase to the inducedemf ?
D.C. potentiometer is an instrument to measure
The commonly used material for thermocouple is
Impedance matching transformers are used for
The maximum load that a power transformer can carry is limited by its
A magnetisation curve represents the relationship between
If the synchronous fails to pull into synchronism after applying dc field current, the probablecause may be
In a 3phase induction motor crawling happens at
The circuit shown in figure will consume power of
In cogging the motor
Induction motors provided with open slots have
If the torque speed characteristics of a motor is represented by figure the motor is likely to be
The speed of synchronous motor can be changed by varying
In moving iron instruments, the iron moves in a direction to cause
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