MCQOPTIONS
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MCQOPTIONS
This section includes 1800 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 401. |
In ZRC (s) = 0 at s = ∞, the last element in first Cauer form is |
| A. | R |
| B. | C |
| C. | R and C in series |
| D. | R and C in parallel |
| Answer» C. R and C in series | |
| 402. |
Two sinusoidal voltage sources v1 = 50 sin (100t) and v1 = 50 sin (100t + p) are connected in parallel and fed an inductance XL = 2Ω. The cuirent through XL is |
| A. | 25 A |
| B. | about 17.5 A |
| C. | zero |
| D. | 50 A |
| Answer» D. 50 A | |
| 403. |
A copper coil has a resistance of 40 ohm at 20°C. At 100°C the resistance is likely to be |
| A. | 44 Ω |
| B. | 54 Ω |
| C. | 84 Ω |
| D. | 104 Ω |
| Answer» C. 84 Ω | |
| 404. |
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 |
| A. | increases |
| B. | decreases |
| C. | remains constant |
| D. | may increases or decreases |
| Answer» D. may increases or decreases | |
| 405. |
In figure, the ratio V(s)/I(s) is |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» E. | |
| 406. |
Resistivity of semiconductors is around 100 Ω-m. |
| A. | True |
| B. | False |
| C. | May be True or False |
| D. | can't say |
| Answer» C. May be True or False | |
| 407. |
The impedance of an RC series circuit is 12 Ω at f= 50 Hz. At f= 200 Hz, the impedance will be |
| A. | more than 12 |
| B. | less than 3 |
| C. | more than 3 Ω but less than 12 Ω |
| D. | more than 12 Ω but less than 24 Ω |
| Answer» D. more than 12 Ω but less than 24 Ω | |
| 408. |
A capacitor stores 0.15C at 5 V. Its capacitance is |
| A. | 0.75 F |
| B. | 0.75 μF |
| C. | 0.03 F |
| D. | 0.03 μF |
| Answer» D. 0.03 μF | |
| 409. |
A two branch parallel circuit has a 20 Ω resistance and 1 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 input impedance of the circuit is |
| A. | 500 Ω |
| B. | 50 Ω |
| C. | 20 Ω |
| D. | 5 Ω |
| Answer» B. 50 Ω | |
| 410. |
In figure the switch has been in position 1 for a long time. At t = 0, the switch is moved to position 2. The equation for transient current is |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» D. D | |
| 411. |
An inductance having XL = 5 Ω and a capacitance having XC = 5 Ω are connected in parallel across 100 V, 50 Hz supply. The current drawn from source is |
| A. | zero |
| B. | 20 A |
| C. | 40 A |
| D. | 28.28 A |
| Answer» B. 20 A | |
| 412. |
In attenuation band, β is an odd multiple of π. |
| A. | True |
| B. | False |
| C. | May be True or False |
| D. | can't say |
| Answer» B. False | |
| 413. |
Consider the following statement :If a network has an impedance of (1 - j) as a specific frequency, the circuit would consist of series 1. R and C2. R and L3. R, L and C Which of the statement are correct? |
| A. | 1 and 2 |
| B. | 1 and 3 |
| C. | 1, 2 and 3 |
| D. | 2 and 3 |
| Answer» C. 1, 2 and 3 | |
| 414. |
In an R-L-C circuit, v(t) = 20 sin (314 t + 5 π/6) and i(t) = 10 sin (314 t + 2π/3). The p.f of the circuit is |
| A. | 0.5 lead |
| B. | 0.866 lag |
| C. | 0.866 lead |
| D. | 0.5 lead |
| Answer» C. 0.866 lead | |
| 415. |
Consider the following statements for a driving point function F(jω): 1. Re F(jω) is an even function of ω and is 0 or positive for all values of ω.2. Im F(jω) is an even function of ω and is 0 or positive for all values of ω.3. Re F(jω) is an odd function of ω and is 0 or negative for all values of ω.4. Re F(s) = 0 for Re s = 0. Which one of the statements given above is/are correct? |
| A. | 1 only |
| B. | 1 and 4 |
| C. | 2, 2 and 4 |
| D. | 4 only |
| Answer» B. 1 and 4 | |
| 416. |
Fourier transform and F(jω) of a signal f(t) has the property |
| A. | F(jω) = F(-jω) |
| B. | F(jω) = -F(-jω) |
| C. | F(jω) = F*(jω) |
| D. | F(jω) = -F*(-jω) |
| Answer» C. F(jω) = F*(jω) | |
| 417. |
Current density J, conductivity σ and electric field E in a conductor are related as |
| A. | J = σE |
| B. | σ = JE |
| C. | Ѱ = E/σ |
| D. | J = σE² |
| Answer» B. σ = JE | |
| 418. |
An RLC series circuit has R = 30 Ω, XL = 30 Ω and XC = 30 W. Its impedance is |
| A. | 30 ∠0°. |
| B. | 30 ∠45° |
| C. | 42.42 ∠45° |
| D. | 90 ∠45°. |
| Answer» B. 30 ∠45° | |
| 419. |
A 20 Ω resistor, a 1H inductor and 1μF capacitor are connected in parallel the combination is driven by a unit step current. Under the steady state, source current flows through |
| A. | inductor |
| B. | capacitor |
| C. | resistor |
| D. | all |
| Answer» B. capacitor | |
| 420. |
For a transmission line open circuit and short circuit impedances are 20 Ω and 5 Ω. Then characteristic impedance is |
| A. | 100 Ω |
| B. | 50 Ω |
| C. | 25 Ω |
| D. | 10 Ω |
| Answer» E. | |
| 421. |
An RL series circuit is initially relaxed. A step voltage E is applied. If t is time constant, voltage across R and L will be equal at t = |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» C. C | |
| 422. |
A source of angular frequency 1 rad sec has a source impedance consisting of 1 Ω resistance in series with 1 H inductance. The load that will obtained the maximum power transfer is |
| A. | 1 Ω resistance |
| B. | 1 Ω resistance in parallel with 1 H inductance |
| C. | 1 Ω resistance in series with 1 F capacitor |
| D. | 1 Ω resistance in parallel with 1 F capacitor |
| Answer» D. 1 Ω resistance in parallel with 1 F capacitor | |
| 423. |
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 |
| A. | 25 W |
| B. | 50 W |
| C. | 125 W |
| D. | 250 W |
| Answer» D. 250 W | |
| 424. |
An RC circuit initially at rest has a step signal. The response V(t) across C is V(t) = 1 - e^(-at), If now there is an initial voltage on C of 2 volts for the same step signal, V(t) is now |
| A. | 1 + e^(-at) |
| B. | 1 + 2e^(-at) |
| C. | 2 - e^(-at) |
| D. | 3 - e^(-at) |
| Answer» B. 1 + 2e^(-at) | |
| 425. |
A series resonant circuit has R = 2 Ω, L = 0.1 H and C =10 μF. At resonance applied voltage = 10 ∠0 V. Voltage across inductance is likely to be |
| A. | 10 ∠0 V |
| B. | 10 ∠45° V |
| C. | 100 ∠90° V |
| D. | 100 ∠-90° V |
| Answer» D. 100 ∠-90° V | |
| 426. |
If impedance of a circuit is defined by the following equation, then circuit is said to be in resonance if |
| A. | ab = cd |
| B. | bc = ad |
| C. | ac = bd |
| D. | none |
| Answer» C. ac = bd | |
| 427. |
Which one is correct option?1. A pure capacitor never dissipates energy, but only stores.2. Capacitor can store finite amount of energy even cunent is zero.3. The current through a capacitor is zero if voltage across it d.c.4. Voltage across a capacitor cannot change instantaneously since it would require an infinite current.5. qc(0-) = qc(0+) |
| A. | 5, 4, 3, 2 |
| B. | 3, 4, 1, 2 |
| C. | 2, 4, 3, 1 |
| D. | 1, 2, 3, 4, 5 |
| Answer» E. | |
| 428. |
In an underdamped RLC series circuit, the natural frequency is ωn. The frequency of damped oscillations is |
| A. | ωn |
| B. | less than ωn |
| C. | more than ωn |
| D. | 2 ωn |
| Answer» C. more than ωn | |
| 429. |
The graph of a network is shown in the figure. Which one of the figure shown is not a tree of the graph? |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» E. | |
| 430. |
A parallel plate capacitor with air as dielectric has a capacitance C. If the dielectric has a dielectric constant ∈ᵣ and the remaining dimensions are the same, the capacitance will be |
| A. | C/∈ᵣ |
| B. | ∈ᵣC |
| C. | ∈²rC |
| D. | ∈³rC |
| Answer» C. ∈²rC | |
| 431. |
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 |
| A. | less than 3 A |
| B. | equal or less than 3 A |
| C. | equal to or less or more than 3 A |
| D. | 1.5 A |
| Answer» B. equal or less than 3 A | |
| 432. |
The frequency at which maximum voltage occurs across the capacitance in R-L-C series circuits is given by |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» B. B | |
| 433. |
Assertion (A): Energy stored in inductance is LI²/2 and that in capacitance is CV²/2.Reason (R): Inductance and capacitance are dual of each other. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true and R is not the correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true and R is not the correct explanation of A | |
| 434. |
When a circuit is excited by ac sinusoidal source, the admittance is obtained by letting s = jω in Y(s). |
| A. | True |
| B. | False |
| C. | May be True or False |
| D. | can't say |
| Answer» B. False | |
| 435. |
When a series RL circuit having power factor angle 0 is switched on to an ac voltage Vm sin (ωt + Φ), the transient term is zero if Φ = 0. |
| A. | True |
| B. | False |
| C. | May be True or False |
| D. | can't say |
| Answer» B. False | |
| 436. |
Three resistances of 15 Ω, 10 Ω and 3 Ω are connected in parallel. The overall resistance is |
| A. | less than 3 Ω |
| B. | between 15 and 10 Ω |
| C. | between 10 and 3 Ω |
| D. | more than 3 Ω |
| Answer» B. between 15 and 10 Ω | |
| 437. |
Current having waveform in figure flows through 10 Ω resistance. Average power is |
| A. | 1000 W |
| B. | 500 W |
| C. | 333.3 W |
| D. | 250 W |
| Answer» D. 250 W | |
| 438. |
Assertion (A): In series R-L-C circuit, the current may lead or lag the voltage depending on the value of R.Reason (R): Phase angle of an R-L series circuit is tan¯¹ (ωL/R). |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true and R is not the correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» E. | |
| 439. |
Which of the under-given graphs shown in figure gives variation in resistance of a copper conductor with temperature? |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» C. C | |
| 440. |
A resistance R, inductance L and capacitance C are in series. The source frequency is adjusted to be equal to resonant frequency. The lower half power frequency is ω₁. Another resistance R is added in series with the circuit. The new lower half power frequency will be |
| A. | ω₁ |
| B. | less than ω₁ |
| C. | more than ω₁ |
| D. | either more than ω₁ or less then ω₁ |
| Answer» D. either more than ω₁ or less then ω₁ | |
| 441. |
The resistance of a bulb at the time of full brightness is 1200 Ω. Then the resistance at room temperature is about |
| A. | 1200 Ω |
| B. | 120 Ω |
| C. | 600 Ω |
| D. | 10 Ω |
| Answer» C. 600 Ω | |
| 442. |
A 0.5 μF capacitor is connected across a 10 V battery. After a long time, the circuit current and voltage across capacitor will be |
| A. | 0.5 A and 0 V |
| B. | 0 A and 10 V |
| C. | 20 A and 5 V |
| D. | 0.05 A and 5 V |
| Answer» C. 20 A and 5 V | |
| 443. |
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 |
| A. | over damped |
| B. | critically damped |
| C. | under damped |
| D. | any of the above depending the magnitude of voltage |
| Answer» C. under damped | |
| 444. |
In a series RC circuit Z = (R² + ω²C²)^0.5. |
| A. | True |
| B. | False |
| C. | May be True or False |
| D. | can't say |
| Answer» C. May be True or False | |
| 445. |
For node 2 in figure, KCL equation is |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» C. C | |
| 446. |
A series RLC circuit is supplied from a variable frequency source. The resonant frequency is ω₀. The voltage across L is maximum at a frequency |
| A. | equal to ω₀ |
| B. | slightly less than ω₀ |
| C. | slightly more than ω₀ |
| D. | none of the above |
| Answer» D. none of the above | |
| 447. |
A steel bar needs 1200 AT to magnetise it. The voltage that must be applied to the magnetising coil of 100 turns and 10 Ω resistance is __________ volt. |
| A. | 120 |
| B. | 12 |
| C. | 1200 |
| D. | 10 |
| Answer» B. 12 | |
| 448. |
A function f(t) = k e^(at) is __________ for (a > 0). |
| A. | stable |
| B. | unstable |
| C. | marginal |
| D. | none |
| Answer» C. marginal | |
| 449. |
A current wave is i = 100e^(-60t) The initial and final values of current are |
| A. | 100 and 50 |
| B. | 100 and 0 |
| C. | 0 and 100 |
| D. | 100 and 100 |
| Answer» C. 0 and 100 | |
| 450. |
In the set of equation |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» B. B | |