InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 251. |
Two phasors having rms values V and V which are added to give a phasor having rms value V. V is maximum if phase angle between V and V is |
| Answer» Sum of phasors is maximum if they are in phase and 360° = 0. | |
| 252. |
A current of 1 A in the coil of an iron cored electromagnet cause a flux density of 0.2.T. If the current is 2 A, B= |
| Answer» In air cored coil flux density increases linearly with current because there is no saturation. | |
| 253. |
A 2 mH inductor with some initial current can be represented as shown below, where is the Laplace transform variable. The value of initial current is |
| Answer» Initial current iL(0+) or . | |
| 254. |
As temperature increases, the temperature coefficient of metals increases. |
| Answer» As temperature increases the temperature coefficient of metal decreases. | |
| 255. |
In a 3 phase system, the zero sequence component of line to line voltages is zero |
| Answer» Zero sequence component of line to line voltage is always zero irrespective of degree of unbalance. | |
| 256. |
An RLC series circuit has R = 30 Ω, X = 30 Ω and X = 30 W. Its impedance is |
| Answer» Z = 30 + j (30 - 30) = 30∠0 Ω. | |
| 257. |
R, L and C are in parallel. The circuit is switched on to a constant current source I at = 0. At = ∞ the current through inductance is I. |
| Answer» At t = ∞ inductance behaves as short-circuit. | |
| 258. |
Magnetic effect of current is used in generators but not in motors. |
| Answer» Magnetic effect of current is used in both generators and motors. | |
| 259. |
For a nonlinear resistance |
| Answer» In a non-linear resistance v-i graph is a curve. | |
| 260. |
The Z parameters Z and Z for the 2-port network in the figure. |
| Answer» Apply mesh analysis in both loop 11E1 = 6I1 + 4I2, E2 + 10 E1 = 4 (I1 + I2) Z21 . | |
| 261. |
For the wave shown in figure, the average value is |
| Answer» Since area of triangle is half of the rectangle enclosing it, average value = 0.5 x peak value. | |
| 262. |
In figure, A is ideal ammeter having zero resistance. It will read __________ ampere. |
| Answer» | |
| 263. |
Threshold of perception occurs at a current of about 1 mA. |
| Answer» Threshold of perception means current which causes small sensation in body. | |
| 264. |
The current wave shown in figure is applied by a 0.1 F capacitor at = 0. At = 0, the voltage across capacitor is |
| Answer» Voltage across a capacitor cannot change instantaneously. | |
| 265. |
The average value of delayed full wave rectified sine wave (figure) is |
| Answer» . | |
| 266. |
A current increasing at the rate of 1 A/s is passed through 1 F capacitor. At = 0, = 0. The charge stored after 1 second is |
| Answer» q = i dt | |
| 267. |
In figure, the voltage V = 4∠0 V. The source voltage V is |
| Answer» IR = 2∠OA, I1 = 2∠-90° = -j 2A. Total current = 2 - j2. V2 = 2 (2 - j2) + 4∠0 = 8 - j4 volts. | |
| 268. |
A capacitor whose capacitance C = C (1- cos ω) is fed by a sinusoidal voltage = V sin ω. The equation for current is |
| Answer» i = or i = C0 (1 - cos ωt) ωV0 cos ωt = C0ωV0 (cos ωt - cos2 ωt) | |
| 269. |
Figure shows an RC circuit. The magnitude plot V/V |
| Answer» | |
| 270. |
A two branch parallel circuit has a 10 Ω resistance and 0.5 H inductance in one branch and a 100 μF capacitor in the second branch. It is fed from 100 V ac supply. At resonance, the source current is |
| Answer» At parallel resonance source current = | |
| 271. |
In the circuit shown in the given figure, R will absorb maximum power when its value is |
| Answer» Circuit can be rearranged as follows Now find and find RL = ?. | |
| 272. |
In an RC series circuit excited by dc voltage E, the current at = 0 is |
| Answer» Since the capacitor does not have any charge initially, | |
| 273. |
The current through a 10 Ω resistance in a dc circuit having two emf sources is 3A. If this resistance is changed to 20 Ω, the new value of current will be |
| Answer» The current will be less than 3 A. It may not be 1.5 A because other resistance in the circuit also affect the value of current. | |
| 274. |
In the figure circuit, V = 40 V. When R is 10 Ω. When R is zero, the value of V will be |
| Answer» When R = 0, it will be short circuited and 10 Ω and 20 Ω will come in series, and potential across V1 will become 40 V by divider rule. | |
| 275. |
Insulation resistance of a cable is directly proportional to its length. |
| Answer» Insulation resistance is inversely proportional to length. | |
| 276. |
The equivalent circuit of a resistor is shown in the given figure. The resistor will be non-inductive if |
| Answer» Rationalize the function and find the value of R. | |
| 277. |
For a series RLC circuit bandwidth is ω - ω = R/2L. |
| Answer» . | |
| 278. |
A planar graph has 6 nodes and 7 branches. The number of meshes in the dual graph is |
| Answer» In dual, node pairs and meshes are interchanged b = (n - 1) + l l = 2. | |
| 279. |
An ac voltage 20 sin 1000 feeds an R-C series circuit. R = 8 Ω and active power is 4 W. The power factor is |
| Answer» or or | |
| 280. |
For a sine wave the average value is calculated over half the cycle. |
| Answer» The average value over full cycle is zero. | |
| 281. |
Two resistances of 2 Ω each are connected in series. A shunt having zero resistance is connected across the combination. The overall resistance will be |
| Answer» | |
| 282. |
The poles and zeros of a positive real function |
| Answer» Only then it is possible to synthesize by R, L and C elements. | |
| 283. |
In a linear circuit, the superposition principle can be applied to calculate the |
| Answer» Apply KVL (4 - I) 10 + 4 (9 - I) = 5 I I = 4A P = I2.R 80 W. | |
| 284. |
If A = 7 ∠15, A is |
| Answer» | |
| 285. |
The colour coding of a resistors shows 100 K, ± 10%. When the resistance was measured with an ohmmeter, it read |
| Answer» Ohmmeter measured 100 K ± 10/2 95 Ω. | |
| 286. |
The output voltage of a charger is |
| Answer» The charger has to supply current to battery for charging. This is possible only if voltage of charger is more than that of battery. | |
| 287. |
The circuit in figure has reached steady values with switch open. If switch is closed at = 0 the voltage across 2 μF capacitance at = 0 is |
| Answer» At t = 0-, VC = 0 and voltage across a capacitor cannot change instantaneously. | |
| 288. |
The current through a 1 mH inductance is () = 2.56 x 10 - 4 x 10 for 2 ≤ ≤ 20 μ sec. The voltage across the inductor is |
| Answer» 1 x 10-3 (2.56 x 10-2 - 4 x 103t) = 1 x 10-3 x 4 x 103 4 volt. | |
| 289. |
An RL impedance function can also be realized as |
| Answer» RL impedance function and RC admittance have similar forms. | |
| 290. |
A step voltages is applied to RLC series circuit having R = 2 Ω, L = 1 H and C = 1 F. The transient current response will be |
| Answer» . Since R = Rcr, critically damped response. | |
| 291. |
Class C solid insulators should not be used above 100°C. |
| Answer» For class C insulators temperature limit is 180°C. | |
| 292. |
An R-L series circuit has R = 5 Ω and L = .01 H. It is fed by ac 50 Hz supply. The rms current in the circuit is 5 A. The active power supplied by the source is |
| Answer» P = I2R = 52(5) = 125 W. | |
| 293. |
A particular current is made up of two components 10A dc and sinusoidal current of peak value 14.14A. The average of resultant current is |
| Answer» The average of sinusoid over 1 cycle is zero. | |
| 294. |
In figure, the switch is closed at = 0. After some time = 6A and rate of change of current was 4A/s. The value of inductor is |
| Answer» Steady state current = A. Therefore, i = (1 - e-3t/L) = 6A and From these equations L = 0.5H. | |
| 295. |
In figure the switch has been in position 1 for a long time. At = 0, the switch is moved to position 2. The equation for transient current is |
| Answer» When switch is in position 2, time constant is | |
| 296. |
In figure the voltage drop across the 10 Ω resistance is 10 V. The resistance R |
| Answer» Current supplied by battery = Therefore current through 2Ω resistance is 11 A. Voltage across R = 48 - 10 - 11 x 2 = 16 V. | |
| 297. |
A capacitor used for power factor correction is single phase circuit decreases |
| Answer» Capacitor is used to improve (increase) p.f. Therefore, line current is decreased for the same active power. | |
| 298. |
Evaluate the value of 2 [ ( - 1) - (1 - 2)] ( ( + 1) + ()) at = 3 sec. |
| Answer» 2[u(2) - u(1 - 6)] [u(4) + u(3)] 2 [1 - 0] [1 + 1] 4. | |
| 299. |
A constant band pass filter has a pass band from 100 to 400 Hz. The resonant frequency of series and shunt arms is |
| Answer» Resonant frequency of arms in constant k band pass filter = (fc1)(fc2). | |
| 300. |
The circuit in figure is switched on at = 0. At any time , () = |
| Answer» | |