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.
| 201. |
The electric energy required to raise the temperature of a given amount of water is 1000 kWh. If heat losses are 25%, the total heating energy required is __________ kWh. |
| Answer» Total heating energy required = 1000 kWh + 25% of 1000 kWh. | |
| 202. |
If = 110 sin (ω + /3) and = 5 sin (ω - /3), the impedance of the circuit is |
| Answer» | |
| 203. |
Ohm's law is valid for |
| Answer» KCL and KVL are valid for voltages and currents of all wave shapes during transient as well as steady state conductions. | |
| 204. |
The dc voltage applied to an R-L series circuit is suddenly changed from V to V. The expression for transient current is |
| Answer» The final steady state current is and transient term must depend on both V1 and V2. | |
| 205. |
One ampere means the flow of |
| Answer» As per definition one ampere means 1 coulomb per second. | |
| 206. |
As the diameter of a wire is doubled, the resistance becomes |
| Answer» Since diameter is doubled, area of cross-section becomes four times and resistance is inversely proportional to area of cross-section. | |
| 207. |
A series resonant circuit has R = 10 Ω, L = 1 μH and C = 1 mF. If R is increased to 20 Ω the resonant frequency |
| Answer» fr depends only on L and C. | |
| 208. |
In figure, V = |
| Answer» Use superposition theorem. | |
| 209. |
In figure, the effective resistance across AB is |
| Answer» Convert the inner star into delta. | |
| 210. |
When R and C are connected in parallel, phase angle of Y is positive. |
| Answer» I = YV. Since I leads V, phase angle of Y must be positive. | |
| 211. |
An RLC series circuit is excited by an ac voltage = 1 sin. If L = 10 H, C = 0.1 F peak value of voltage across R is |
| Answer» It is a series resonant circuit and peak voltage across R is equal to peak value of source voltage. | |
| 212. |
If all other parameters are the same, a capacitor with mica as dielectric has higher capacitance than air capacitor. |
| Answer» C ∝ ∈r . | |
| 213. |
If V = 100 ∠ 16°, the is |
| Answer» | |
| 214. |
In the circuit shown, the steady state is reached with S open S is closed at = 0, the current I in the 1 Ω resistor connected is to be determined at = 0 is given by |
| Answer» If steady is reached L will be short circuited the current in 1 Ω resistor I = 4/2 2A. It will act as current source in parallel with inductor. Now apply superposition theorem consider 4 volt source, current source will be open and inductor also open. Current in R' = 1 Ω resistor = 2A. When current source consider, voltage source will be short circuited and current due to inductor is 1A in opposite direction. Total current 2 - 1 = 1 A. | |
| 215. |
The value of the inductance of coil in which a current increases linearly from zero to 0.1A in 0.2 second producing a voltage of 5 volts is __________ . |
| Answer» 10 = L L = 10 H. | |
| 216. |
The purpose of earthing electric appliances is |
| Answer» Earthing prevents electric shock because the fault current flows through the earth conductor and not through body. | |
| 217. |
Three impedances (3 + 4) Ω each are connected in star. The impedances of equivalent delta circuit will be |
| Answer» | |
| 218. |
Find V in the circuit |
| Answer» There is no independent source hence VTH = 0. | |
| 219. |
In an R-L-C series circuit, R = 2/ . If R is doubled |
| Answer» Increase of resistance increases damping. | |
| 220. |
The Gaussian filter characteristic figure is realizable. |
| Answer» It is realizable because |log|H(jω)|| = ω2. | |
| 221. |
A coil of resistance R and inductance L is connected in series with 10 mF capacitor. The resonant frequency is 1000 Hz. Another 10 F capacitor is connected in parallel with the above capacitor. The new resonance frequency will be |
| Answer» Total capacitance increases and therefore ωr decreases. | |
| 222. |
The circuit is figure, is in steady state with switch closed. At = 0 switch is opened. The current is |
| Answer» The initial current through inductance is | |
| 223. |
The voltage of the source in circuit shown __________ if () = - 20 is |
| Answer» Voltage across capacitor = i(t) x 1 - 20 e-2t Current across capacitor = 120 e-2t Source current Is = iC (t) + iR(t) 120 e-2t - 20e-2t 100 e-2t VR = 100 e-2t 33.33 e-2t, Vs = 100 e-2t - 20 e-2t - 33.33 e-2t Vs = 46.6 e-2t volt. | |
| 224. |
In an underdamped RLC series circuit, the natural frequency is ω. The frequency of damped oscillations is |
| Answer» In underdamped circuit the frequency of oscillations is less than resonant frequency. | |
| 225. |
The equivalent inductance measured between the terminals 1 and 2 for the circuit shown in the figure is |
| Answer» L = L1 + L2 - 2M because currents are opposing. | |
| 226. |
A dc network has 3 independent nodes and 4 loops. In total analysis, the number of equations is |
| Answer» The number of nodal equations is one less than the number of independent nodes. | |
| 227. |
In the circuit, S was initially open. At time = 0, S is closed. When the current through the inductor is 6 A, the rate of change of current through the resistor is 6 A/s. The value of the inductor would be |
| Answer» i = 18(1 - e-t/L) ...(1) 6 = 8 (1 - e-t/L) 1 = 3 (1 - e-t/L) 1 = 3 - 3 e-t/L e-t/L = 2/3 from (1) . | |
| 228. |
A current of 1 A in the coil of an iron cored electromagnet causes B = 0.5T. If current is 2A, B = |
| Answer» If saturation starts B will be less than it. | |
| 229. |
Two current sources each of rms value 10 A have frequencies 40 Hz and 50 Hz respectively. They are connected in series, the expression for resultant wave is |
| Answer» Peak value = 14.14 A; ω1 = 2p x 40, ω2 = 2p x 50 | |
| 230. |
To find the current in a 20 Ω resistance connected in a circuit, Norton's theorem is used. I = 7.5 A. The current though 20 Ω resistance. |
| Answer» Norton's equivalent is as shown in figure. Some current will flow through RN. There-fore, current through 20Ω resistance is less than 7.5 A. | |
| 231. |
While calculating Norton's resistance, all current sources are short circuited. |
| Answer» All current sources are open circuited. | |
| 232. |
If V = 4 in the figure, the value of I is given by |
| Answer» At node V1 at node V2 2V2 - V1 = 0 V1 = 2V2 V2 = 4 V1 = 8 Is = x 8 - 4 = 6A. | |
| 233. |
A series circuit has R = 5 Ω and C = 10 μF. It is switched on to a 12 V dc battery at = 0. The current in the circuit will be maximum |
| Answer» In RC circuit excited by a dc battery of voltage E, and is maximum at t = 0+. | |
| 234. |
A heater is rated at 230 V, 5 A AC. Then |
| Answer» In heaters, the ratings are specified in terms of rms values. | |
| 235. |
KCL is a statement of principle of conservation of energy. |
| Answer» KCL is restatement of principle of conservation of charge. | |
| 236. |
Two passive elements are connected in series and a dc voltage is applied to the circuit. The time variation of the current is shown in figure. The two elements are |
| Answer» In an RL circuit excited from dc source the current rises exponentially with a time constant | |
| 237. |
Which statement is incorrect for parallel resonance? |
| Answer» At parallel resonance Z is maximum and Y is minimum. | |
| 238. |
If a capacitor is charged by a square wave current source the voltage across the capacitor is |
| Answer» Capacitor will behave as integrator. | |
| 239. |
The equivalent resistance between terminals and figure is |
| Answer» Use star-delta conversion. | |
| 240. |
A system function the resonant frequency in rad/sec and bandwidth in rad/sec. is given by |
| Answer» ωn = 10 2 ζωn = 4 ζωn = 2, and ζ =0.2 ωr = ωn1 - ζ2 ωr = 10 1 - ζ2 10 Bandwidth = 4 By comparing the formula then Bandwidth is equal to a. | |
| 241. |
The temperature coefficient of copper is 0.00393 at 20° C. At 50° C the temperature coefficient is |
| Answer» The temperature coefficient decreases slightly with increase in temperature. The equation is | |
| 242. |
To determine the polarity of voltage drop across a resistor, it is sufficient to know |
| Answer» Polarity of voltage depends only on direction of current and nothing else. | |
| 243. |
A sawtooth current wave is passed through a resistance |
| Answer» V = IR and P = I2R. Therefore, waveshape of V is the same as that of I but waveshape of P is different. | |
| 244. |
In the circuit, V = 10 cos ω, power drawn by the 4Ω resistor is 8 watt. The power factor is |
| Answer» I2m = P/R Im = 2 Total power drawn = I2R x 2 x [4 + 2] 6 VmIm cos θ = 6 x 10 x 2 x PF = 6 P.F = 0.85 . | |
| 245. |
The current voltage relation for an inductance L is |
| Answer» | |
| 246. |
A band elimination constant filter has series resonant circuit in series arms. |
| Answer» It has parallel resonant circuit in series arms. | |
| 247. |
A series RLC circuit is at resonance at 200 Hz. If capacitance is increased to four times, the circuit will be in resonance at |
| Answer» . If C becomes four times, f is reduced to half. | |
| 248. |
If the L.T. of the voltage across a capacitor of value 1/3 F is , then the value of the current through the capacitor at = 0 is |
| Answer» t → 0+ s → ∞ and s3 >> s2 >> s >> 1 . | |
| 249. |
In figure, the current I is |
| Answer» I4 = I1 + I2 + I3 or I4 = 5∠90° + 5∠0 + 5∠180° = 5∠90°. | |
| 250. |
For the circuit shown in the figure, the current I is |
| Answer» V must be given. | |