Explore topic-wise InterviewSolutions in .

Correct OPTION is (a) 15 F

Easiest explanation: When TWO CAPACITANCES are connected in PARALLEL their equivalent capacitance is equal to the sum of the INDIVIDUAL capacitances. Ceq=(C1+C2)=15 F.

Correct option is (a) 1 Ω

The best I can EXPLAIN: When two RESISTANCES are connected in parallel their equivalent resistance is equal to the HARMONIC mean of the individual resistances. Req=R1.R2÷(R1+R2)=22 Ω.

Correct option is (a) True

To elaborate: BANDWIDTH is defined as the range of FREQUENCIES for which the SIGNAL exists. Selectivity is inversely proportional to the bandwidth. Lower the bandwidth lower will be the COST.

Correct choice is (b) 0

The best explanation: The quality factor is defined as the RATIO of the reactive power to the active power consumed. The resistor ALWAYS ABSORBS active power. The value of reactive power consumed is 0. Quality factor=0/P=0.

The CORRECT choice is (b) 1÷R

Explanation: The minimum value of the ADMITTANCE in case of the parallel RLC network is R. During RESONANCE condition Xl=Xc so Y=1÷Z=(R^2+(Xl-Xc)^2)^.5=1÷R.

Correct option is (b) False

Explanation: LOOP is DEFINED as the CLOSED path which can contain small closed paths. Mesh does not contain any closed path. All meshes are loops but vice-versa is not TRUE.

Right CHOICE is (a) True

For EXPLANATION: The mesh analysis is one of the network TOOLS to find the responses in the circuits. It is only applicable to PLANAR circuits. Planar circuits are 2-D circuits as mesh analysis involves mesh circulating CURRENTS.

Right option is (d) 24 J

Easiest explanation: The energy STORED in the inductor is .5×Leq×I^2. The VALUE of Leq=1+2=3 H. The total AMOUNT of energy stored in the inductor in the STEADY state CONDITION. E=.5×eq×I^2=.5×3×4×4=24 J.

Right choice is (c) Linear, Bilateral

The BEST I can explain: The nature of the ELEMENT is linear and bilateral. It follows the principle of homogeneity and law of ADDITIVITY. For bilateral nature, it should be SYMMETRICAL in the first and third QUADRANT.

The correct choice is (d) infinite

Best explanation: Impulse function is neither an ENERGY SIGNAL nor a power signal. It is a pulse of infinite amplitude and ZERO width. The value of impulse is 0 for TIME not equal to zero.

Right answer is (B) 1

Explanation: Unit step FUNCTION is DISCONTINUOUS at t=0. The value of the unit step function is 1 for t>0 and zero for t<0. It is right handed and bounded signal.

The CORRECT ANSWER is (a) Indirect field oriented CONTROL

Easiest explanation: IFOC STANDS for indirect field oriented control. DTC and IFOC are the techniques used for controlling the speed and torque of a 3-phase induction motor.

Correct option is (B) False

The explanation is: The REACTIVE power is DEFINED as the product of the voltage, current, and sine of the difference between the phase angle of voltage and current. In the case of a capacitor, the voltage lags the current. The value of sine is NEGATIVE and reactive power is negative.

Right ANSWER is (a) True

To explain: The reactive power is DEFINED as the product of the voltage, current, and SINE of the difference between the PHASE angle of voltage and current. In the case of an INDUCTOR, the voltage leads the current. The value of sine is positive and reactive power is positive.

The correct choice is (B) nL H

For explanation I would say: When two INDUCTORS are CONNECTED in series their equivalent inductance is equal to the sum of the individual inductances. Leq=L+L+…..+n times L=nL H.

Correct answer is (a) inf

Best explanation: The QUALITY factor is defined as the ratio of the reactive power to the active power CONSUMED. The pure capacitor always absorbs reactive power. The VALUE of active power consumed is 0. Quality factor=Q/0=inf.

The correct CHOICE is (a) inf

The BEST I can explain: The quality factor is defined as the ratio of the reactive power to the active power CONSUMED. The purely INDUCTIVE coil always ABSORB reactive power. The value of active power consumed is 0. Quality factor=Q/0=inf.

The correct CHOICE is (a) R

To elaborate: The minimum value of the SERIES impedance in case of the series RLC network is R. During RESONANCE CONDITION Xl=Xc so Z=(R^2+(Xl-XC)^2)^.5=R.

Right option is (a) True

For EXPLANATION: In the case of the dead NETWORK there are no independent sources available in the electrical circuit. The Thevenin voltage of the circuit is zero because no force is available to DRIVE the current in the circuit.

The correct answer is (b) False

For EXPLANATION: The NETWORK is defined as the INTERCONNECTION of electrical elements that may or may not has a CLOSED path. The circuit is defined as the interconnection of an element that must have at least one closed path. All networks are not always circuits but vice-versa is true.

The correct option is (a) 400 J

Explanation: The ENERGY STORED in the capacitor is .5×C×V^2. It is the TOTAL amount of energy stored in the capacitor in the STEADY state condition. E=.5×C×V^2=.5×2×20×20=400 J.

Correct ANSWER is (b) PLUGGING

Explanation: Plugging is the BEST braking method among all braking techniques. In plugging the value of the armature current reverses and the mechanical energy is EXTRACTED. A very high braking torque is PRODUCED in case of plugging.

Correct CHOICE is (b) Ideal current and voltage source

To explain: Source transformation is not valid for an ideal current and voltage source. The INTERNAL resistance for ideal voltage and current source is zero DUE to which source transformation is not valid.

Right choice is (a) inf MW

Best explanation: The resistor is a linear element. It only absorbs REAL power and dissipates it in the form of heat. The voltage and CURRENT are in the same PHASE in CASE of the resistor so the ANGLE between V & I is 0°. P=I^2R=0×0×inf=inf MW.

Correct option is (a) -900 W

Best EXPLANATION: When the current enters the POSITIVE terminal of an element it will always absorb the power and when the current leaves the positive terminal it will DELIVER the power. Power DELIVERED is -15×60=-900 W.

Correct OPTION is (a) -30 W

The EXPLANATION is: When the current enters the positive terminal of an ELEMENT it will ALWAYS absorb the power and when the current leaves the positive terminal it will deliver the power. Power delivered is -5×6=-30 W.

The correct choice is (a) 12 Ω

The BEST I can explain: When three resistances are CONNECTED in series their EQUIVALENT resistance is equal to the sum of the INDIVIDUAL resistances. Req=R1+ R3+R2=12 Ω.

The correct OPTION is (a) 13 H

Explanation: When two inductors are connected in SERIES their equivalent inductance is EQUAL to the SUM of the INDIVIDUAL inductances. Leq=L1+L2=4+9=13 H.

The correct option is (b) 0 V

To ELABORATE: During the short circuit condition, the voltage is equal to zero volts. According to OHM’s law, V=IR=0 V. The VALUE of the current can be positive, negative or zero.

The correct option is (a) Starting

The best explanation: Wound ROTOR induction MOTOR has better starting characteristics because external resistance can be connected to it using slip rings to start the motor. In the case of SCIM, no external resistance can be connected to the rotor side.

The correct choice is (a) Networks

The explanation is: The network is defined as the INTERCONNECTION of electrical ELEMENTS that may or may not has a closed path. The CIRCUIT is defined as the interconnection of an element that must have at LEAST one closed path. All circuits are ALWAYS networks but vice-versa is not true.

Right option is (a) Squirrel cage induction motor

To EXPLAIN I would SAY: SCIM stands for squirrel cage induction motor. SCIM ROTOR is made up of aluminum, copper bars. There are no armature conductors INVOLVED in it.

The correct option is (a) True

For explanation I would SAY: In regenerative braking, the power is fed BACK to the source from the BATTERY. The kinetic energy of the motor shaft is CONVERTED into electrical energy.