Previous Year Questions
48 questions — organised by subject with solutions and explanations.
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The output voltage ( ) of the Schmitt trigger shown in figure swings between +15V and -15V. Assume that the operational amplifier is ideal. The output will change from +15V to -15V when the instantane
The forward resistance of the diode shown in figure is 5 and the remaining parameters are same as those of an ideal diode. The dc component of the source current is
The cut-in voltage of both Zener diode and diode D shown in figure is 0.7 V, while break down voltage of is 3.3 V and reverse breakdown voltage of D is 50 V. the other parameters can be assumed to be
The transfer function of the system described by with u as input and y as output is
A unity feedback system has an open loop transfer function, . The root locus plot is
For the system , which of the following statements is true?
For the system , with u as unit impulse and with zero initial state, the output, y, becomes
The state transition matrix for the system with initial state X(0) is
The frequency of the clock signal applied to the rising edge triggered D flip-flop shown in figure is 10 kHz. The frequency of the signal available at Q is
For the circuit shown in figure, the Boolean expression for the output Y in terms of inputs P, Q, R and S is
The logic circuit used to generate the active low chip select (CS) by an 8085 microprocessor to address a peripheral is shown in figure. The peripheral will respond to addresses in the range.
Consider the circuit shown in figure. If the frequency of the source is 50 Hz, then a value of which results in a transient free response is
A two port network, shown in figure is described by the following equations The admittance parameters for the network shown are
In the circuit shown in figure, the switch is closed at time t=0. The steady state value of the voltage is
A series R-L-C circuit has R= , L= and C= . The lower half power frequency of the circuit is
A first order, low pass filter is given with R=50 and C= . What is the frequency at which the gain of the voltage transfer function of the filter is 0.25?
In the circuit shown in figure, what value of C will cause a unity power factor at the ac source?
In the circuit shown in figure, it is found that the input ac voltage and current i are in phase. The coupling coefficient is , where M is the mutual inductance between the two coils. The value of K a
An 11 V pulse of 10 duration is applied to the circuit shown in figure. Assuming that the capacitor is completely discharged prior to applying the pulse, the peak value of the capacitor voltage is
The graph of an electrical network has N nodes and B branches. The number of links, L, with respect to the choice of a tree, is given by
Two in-phase, 50 Hz sinusoidal waveform of unit amplitude are fed into channel 1 and channel 2 respectively of an oscilloscope. Assuming that the voltage scale, time scale and other settings are exact
The line-to-line input voltage to the 3 phase, 50 Hz, ac circuit shown in figure is 100 V rms. Assuming that the phase sequence is RYB, the wattmeters would read.
The rotor of a three phase, 5 kW, 400V, 50 Hz, slip ring induction motor is wound for 6 poles while its stator is wound for 4 poles. The approximate average no load steady state speed when this motor
A 400V/200V/200V, 50 Hz three winding transformer is connected as shown in figure. The reading of the voltmeter, V, will be
A 1 kVA, 230V/100V, single phase, 50 Hz transformer having negligible winding resistance and leakage inductance is operating under saturation, while 250 V, 50 Hz sinusoidal supply is connected to the
A 200 V, 2000 rpm, 10A, separately excited dc motor has an armature resistance of . Rated dc voltage is applied to both the armature and field winding of the motor. If the armature drawn 5A from the s
A dc series motor fed from rated supply voltage is overloaded and its magnetic circuit is saturated. The torque-speed characteristic of this motor will be approximately represented by which curve of b
The flux per pole in a synchronous motor with the field circuit ON and the stator disconnected from the supply is found to be 25 mWb. When the stator is connected to the rated supply with the field ex
If a 400V, 50 Hz, star connected, 3 phase squirrel cage induction motor is operated from a 400 V, 75 Hz supply, the torque that the motor can now provide while drawing rated current from the supply?
In the chopper circuit shown in figure, the input dc voltage has a constant value . The output voltage is assumed ripple-free. The switch S is operated with a switching time period T and a duty ratio
A step down chopper is operated in the continuous conduction mode in steady state with a constant duty ratio D. If is the magnitude of the dc output voltage and if is the magnitude of the dc input vol
Figure shows an inverter circuit with a dc source voltage . The semiconductor switches of the inverter are operated in such a manner that the pole voltages and are as shown in figure. What is the rms
In the single phase diode bridge rectifier shown in figure, the load resistor is R = 50 . The source voltage is V=200 , where radians per second. The power dissipated in the load resistor R is
A three phase thyristor bridge rectifier is used in a HVDC link. The firing angle a (as measured from the point of natural commutation) is constrained to lie between 5 and 30 . If the dc side current
A six pulse thyristor rectifier bridge is connected to a balanced 50 Hz three phase ac source. Assuming that the dc output current of the rectifier is constant, the lowest frequency harmonic component
Consider a power system with three identical generators. The transmission losses are negligible. One generator has a speed governor which maintains its speed constant at the rated value, while the oth
Consider the problem of relay co-ordination for the distance relays R1 and R2 on adjacent lines of a transmission system figure. The Zone 1 and Zone 2 settings for both the relays are indicated on the
A power system consists of 2 areas (Area 1 and Area 2) connected by a single tie line. It is required to carry out a load flow study on this system. While entering the network data, the tie-line data
A generator is connected to a transformer which feeds another transformer through a short feeder(as shown in figure). The zero sequence impedance values are expressed in pu on a common base and are in
Consider a long, two-wire line composed of solid round conductors. The radius of both conductors is 0.25 cm and the distance between their centers is 1m. If this distance is doubled, then the inductan
A transmission line has a total series reactance of 0.2 pu. Reactive power compensation is applied at the midpoint of the line and it is controlled such that the midpoint voltage of the transmission l
A long wire composed of a smooth round conductor runs above and parallel to the ground (assumed to be a large conducting plane). A high voltage exists between the conductor and the ground. The maximum
Let Y(s) be the Laplace transformation of the function y(t), then the final value of the function is
Fourier Series for the waveform, f(t) shown in figure is
A current impulse , is forced through a capacitor C. The voltage , across the capacitor is given by
What is the rms value of the voltage waveform shown in figure?
Let s(t) be the step response of a linear system with zero initial conditions; then the response of this system to an input u(t) is