MCQOPTIONS
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MCQOPTIONS
This section includes 905 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.
| 351. |
A n-type silicon sample contains a donor concentration of Nd = 2 x 1016 cm-3. The minority carrier hole lifetime is tp0 = 5 μs. The thermal equilibrium generation rate of hole is: |
| A. | 1.125 x 109 cm-3 s-1 |
| B. | 0.625 x 109 cm-3 s-1 |
| C. | 4.5 x 109 cm-3 s-1 |
| D. | 2.25 x 109 cm-3 s-1 |
| Answer» E. | |
| 352. |
A sequential multiplexer is connected as shown in figure. Each time the multiplexer receives the clock, it switches to the next channel from 6 to 1. If the input signals are :A = 10 cos 2p(4 x 103t)B = 15 cos 2p(5 x 103t)C = 20 cos 2p(6 x 103t)D = 10 cos 2p(10 x 103t)The minimum clock frequency should be __________ kHz. |
| A. | 8 kHz |
| B. | 50 kHz |
| C. | 20 kHz |
| D. | 10 kHz |
| Answer» D. 10 kHz | |
| 353. |
Consider the following program segment written for 8085 based system LXI SP, FFFFHMVI A, FFHMOV BB, AK: DCR BPUSH HLJNZ KINR ALXI H, FFCEHCPI 20HLHLDThe contents of accumulator is : |
| A. | CE |
| B. | 20 |
| C. | indeterminate |
| D. | none of these |
| Answer» D. none of these | |
| 354. |
Consider the resonant circuit as shown belowThe circuit is scaled modified so that Zmax 104 and ωo = 108 Radians. Find the required element values |
| A. | R = 104 L = 5 μH C = 20 pF |
| B. | 1000 L = 50 μH C = 200 pF |
| C. | 10 K L = 50 μH C =20 pF |
| D. | None of these |
| Answer» D. None of these | |
| 355. |
The output y(t) of a continuous-time system S for the input x(t) is given by:Which of the following is incorrect? |
| A. | S is linear and time-invariant |
| B. | S is linear and time-varying |
| C. | S is non-linear and time-invariant |
| D. | S is non-linear and time-varying |
| Answer» B. S is linear and time-varying | |
| 356. |
The circuit shown depicts : |
| A. | voltage series negative feedback |
| B. | voltage shunt negative feedback |
| C. | current series negative feedback |
| D. | current shunt negative feedback |
| Answer» E. | |
| 357. |
Consider an incremental vector element of length ΔL and angle between an electric field E and ΔL s cos θ. Then in which direction should ΔL be placed to be obtain maximum value of Δv? |
| A. | In the direction of E |
| B. | In opposite direction of E |
| C. | In the angle of 45° with E |
| D. | In the angle of 60° with E |
| Answer» C. In the angle of 45¬∞ with E | |
| 358. |
Which of the following statements is/are true for the diamond structure? Coordination number is four.Packing fraction is 0.34Copper crystallizes into diamond structureLattice is FCC. |
| A. | 1 only |
| B. | 1, 2 and 4 |
| C. | 2 and 3 only |
| D. | 2, 3 and 4 |
| Answer» C. 2 and 3 only | |
| 359. |
A system described by the transfer function is stable. The constraints on a and K are |
| A. | a > 0, ak < 3 |
| B. | a > 0, ak > 3 |
| C. | a < 0, ak > 3 |
| D. | a < 0, ak < 3 |
| Answer» C. a < 0, ak > 3 | |
| 360. |
Given potential sin Θ cos Φ, find flux density D at (2, 2p, 0) |
| A. | 22.12 pC/m2 |
| B. | 2.212 pC/m2 |
| C. | 22.12 nC/m2 |
| D. | 2.212 nC/m2 |
| Answer» B. 2.212 pC/m2 | |
| 361. |
Consider the frequency modulated signal 10 cos (2p x 105t + 5 sin (2p x 1500t) + 7.5 sin (2p x 1000t) with carrier frequency of 105Hz. The modulation index is |
| A. | 12.5 |
| B. | 10 |
| C. | 7.5 |
| D. | 5 |
| Answer» C. 7.5 | |
| 362. |
Find equivalent capacitance if each capacitance is 1 F. |
| A. | 56 F |
| B. | 6/5 F |
| C. | 6/10 F |
| D. | 5/12 F |
| Answer» C. 6/10 F | |
| 363. |
Given f = GEF + KHIJ + LMON + TUVWXYZ and E + F + G = LMN V + W = U . Z . Y . X . T NAND B(UVW ‚äï WVU) = KJ(XY ‚äï XY)Then f is equivalent to |
| A. | 0 |
| B. | 1 |
| C. | EF + UZ + HI |
| D. | None of these |
| Answer» C. EF + UZ + HI | |
| 364. |
A super heterodyne receiver has an input circuit tuned to a 570 KHz signal. If the intermediate frequency of the amplifier is tuned to 455 KHz. The quality factor Q for a Image Rejection ratio of 125? |
| A. | 100 |
| B. | 56.81 |
| C. | 42.74 |
| D. | 87 |
| Answer» C. 42.74 | |
| 365. |
In amplitude modulation, carrier signals A cos ωt has its amplitude A modulated in proportion with message bearing (low frequency) signal m(t). The magnitude of m(t) is chosen to be __________ . |
| A. | less than 1 |
| B. | less than or equal to 1 |
| C. | more than 1 |
| D. | none of these |
| Answer» C. more than 1 | |
| 366. |
Consider a baseband binary PAM receiver shown below. The additive channel noise n(t) is whit with power spectral density SN(f) = N0/2 = 10-20 W/Hz. The low-pass filter is ideal with unity gain and cutoff frequency 1 MHz. Let Yk represent the random variable y(tk).Yk = nNk if transmitted bit bk = 0Yk = a + Nk if transmitted bit bk = 1Where Nk represents the noise sample value. The noise sample has a probability density function, PNk(n) = 0.5ae-a|n| (This has mean zero and variance 2/a2). Assume transmitted bits to be equiprobable and threshold z is set to a/2 = 10-6 V.The probability of bit error is |
| A. | 0.5 x e-3.5 |
| B. | 0.5 x e-5 |
| C. | 0.5 x e-7 |
| D. | 0.5 x e-10 |
| Answer» E. | |
| 367. |
A uniform plane wave travelling in air is incident on the plane boundary between air and another dielectric medium with er = 15. The reflection coefficient for normal incidence is |
| A. | 0.6 ∠0° |
| B. | 1 ∠0° |
| C. | 0.6 ∠180° |
| D. | 1.2 ∠180° |
| Answer» D. 1.2 ‚à†180¬∞ | |
| 368. |
The expression given is F(A, B , C, D, E, F, G, H) = (33, 48, 102, 158, 222, 229, 233, 243, 255); then the __________ and __________ minterms are grouped together into dual and variable __________ is reduced using the dual |
| A. | 243, 233, D |
| B. | 222, 158, B |
| C. | 243, 255, A |
| D. | 229, 243, E |
| Answer» C. 243, 255, A | |
| 369. |
Which one of the following statements is not correct with regard to power amplifiers? |
| A. | The collector current is large |
| B. | They are used as the front end of multi-stage amplifiers |
| C. | They are used near the end of the multi-stage amplifiers |
| D. | They have a high power rating |
| Answer» C. They are used near the end of the multi-stage amplifiers | |
| 370. |
The correct sequence of subsystems in an FM receiver is |
| A. | Mixer, RF amplifier, Limiter, IF amplifier. Discriminator, Audio amplifier |
| B. | RF amplifier, Mixer, IF amplifier, Limiter, Discriminator, Audio amplifier |
| C. | RF amplifier, Mixer, Limiter, Discriminator IF amplifier, Audio amplifier |
| D. | Mixer, IF amplifier, RF amplifier, Audio amplifier, Discriminator |
| Answer» C. RF amplifier, Mixer, Limiter, Discriminator IF amplifier, Audio amplifier | |
| 371. |
Choose correct option for a stable system : Roots of the characteristic equation of the system are real and negativeArea within the impulse response is finite |
| A. | I is true, II is true |
| B. | I is true, II is false |
| C. | I is false, II is true |
| D. | I is false, II is false |
| Answer» B. I is true, II is false | |
| 372. |
For static electric and magnetic fields in an homogenous source-free medium, which of the following represents the correct form of Maxwell's equations? |
| A. | Δ.E = 0 Δ x B = 0 |
| B. | Δ.E = 0 Δ.B = 0 |
| C. | Δ x E = 0 Δ x B = 0 |
| D. | Δ x E = 0 Δ.B = 0 |
| Answer» E. | |
| 373. |
In a synchro error detector, the output voltage is proportional to [ω(t)]n, where ω(t) is the rotor velocity and n equals : |
| A. | -2 |
| B. | -1 |
| C. | 1 |
| D. | 2 |
| Answer» D. 2 | |
| 374. |
Value of 'K' for the system for which the system is stable: |
| A. | K < 1 |
| B. | K > 1 |
| C. | K < 2 |
| D. | K > 2 |
| Answer» D. K > 2 | |
| 375. |
For a class B amplifier using a supply of VCC = 30 V and driving a load of 16 Ω the maximum efficiency will be __________ . |
| A. | 0.724 |
| B. | 0.7854 |
| C. | 0.624 |
| D. | 0.6854 |
| Answer» C. 0.624 | |
| 376. |
A uniform plane wave is described by the equation H = A/m. If the velocity of the wave is 2 x 108 m/s and εr = 1.8, then. The electric field intensity is |
| A. | 90.35e-j0.1px v/m |
| B. | 903.5e-j0.1px v/m |
| C. | 903.5e-j0.1pz v/m |
| D. | 90.35e-j0.1pz v/m |
| Answer» D. 90.35e-j0.1pz v/m | |
| 377. |
The function f = A ‚äï B ‚äï A ‚äï D ‚äï E ‚äï C ‚äï D ‚äï E ‚äï F ‚äï G ‚äï F ‚äï G ‚äï C ‚äï E ‚äï A ‚äï D ‚äï B ‚äï E ‚äï E ‚äï B ‚äï B ‚äï B ‚äï B ‚äï D can be written as |
| A. | A ‚äï B ‚äï D |
| B. | A ‚äï B ‚äï E |
| C. | A ‚äï E |
| D. | A ‚äï E |
| Answer» E. | |
| 378. |
For the polynomial P(s) = s5 + s4 + 2s3 + 2s2 + 3s + 15 The number of roots which lie in the right half of the s plane is : |
| A. | 4 |
| B. | 2 |
| C. | 3 |
| D. | 1 |
| Answer» C. 3 | |
| 379. |
Assertion (A): The h-parameter model of a BJT can be derived from its hybrid-p model and vice-versa.Reason (R): The hybrid-p model has many more additional elements as compared to h-parameter model of the BJT. |
| A. | Both A and R are individually true and R is the correct explanation of A |
| B. | Both A and R are individually true but 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» C. A is true but R is false | |
| 380. |
If the carrier modulated by a digital bit stream has one of the possible phases of 0°, 90°, 180° and 270°. Then the modulation is called |
| A. | BPSK |
| B. | QPSK |
| C. | QAM |
| D. | MSK |
| Answer» C. QAM | |
| 381. |
The Table given below is the mark obtained by 2 students in 8 different subjects. The regression line of y on x is: |
| A. | y + 0.57x = 9.7558 |
| B. | y - 0.57x = 9.758 |
| C. | 033y + x = 6.335 |
| D. | 0.33y - x = 6.335 |
| Answer» B. y - 0.57x = 9.758 | |
| 382. |
Which of the following functions would have only odd powers of x in its Taylor series expansion about the point x = 0? |
| A. | sin (x3) |
| B. | sin (x2) |
| C. | cos (x3) |
| D. | cos (x2) |
| Answer» B. sin (x2) | |
| 383. |
The current I in the circuit shown in |
| A. | #REF! |
| B. | j1 A |
| C. | 0 |
| D. | 20 A |
| Answer» B. j1 A | |
| 384. |
The input 3-dB frequency is : |
| A. | 100 Hz |
| B. | 148 Hz |
| C. | 100 kHz |
| D. | None |
| Answer» C. 100 kHz | |
| 385. |
Which of the following conditions must be satisfied for a transistor to remain under saturation? Its collector to base junction should be under forward bias.Its collector to base junction should be under reverse bias.Its emitter to base junction should be under reverse bias.Its emitter to base junction should be under forward bias. Select the correct answer from the codes given below: |
| A. | 1 and 2 |
| B. | 1 and 3 |
| C. | 2 and 3 |
| D. | 1 and 4 |
| Answer» E. | |
| 386. |
Determine the voltage VCB in the circuit below: |
| A. | 3.4 V |
| B. | 5.4 V |
| C. | 7.4 V |
| D. | 9.4 V |
| Answer» D. 9.4 V | |
| 387. |
Consider the following statements regarding sources or error in a Q-meter: If a coil with resistance R is connected in direct measurement mode and if the residual resistance of Q-meter is 0.1 R, then the measure Q of the coil would be 1.1 times the actual Q.If the inductance to be measured is less than 0.1 mH, the error due to presence of residual inductance cannot be neglected.The presence of distributed capacitance in a coil modifies the effective Q of the coil. Which of the above statements are correct? |
| A. | 1, 2 and 3 |
| B. | 1 and 2 only |
| C. | 2 and 3 only |
| D. | 1 and 3 only |
| Answer» D. 1 and 3 only | |
| 388. |
If . dt, then F[y(t)] is |
| A. | - jsgn(f). x(f) |
| B. | j2pf . e-jptf . x(f) |
| Answer» B. j2pf . e-jptf . x(f) | |
| 389. |
For the gear train, If θ1 = 2 rad. clockwise and the torque of gear 1 is 10 lb-ft, what is the displacement and torque of gear 7. |
| A. | rad CW, 7.5 lb-ft |
| B. | 4 rad CW, 5 lb-ft |
| C. | rad CW, 7.5 lb-ft |
| D. | rad CW, 7.5 lb-ft |
| Answer» C. rad CW, 7.5 lb-ft | |
| 390. |
If the scattering matrix [S] of a two port network is then the network is |
| A. | lossless and reciprocal |
| B. | lossless but not reciprocal |
| C. | not lossless but reciprocal |
| D. | neither lossless nor reciprocal |
| Answer» D. neither lossless nor reciprocal | |
| 391. |
The figure shown below is designed to act as a constant current source across the load resistor. The β of transistor is 50. What is the value of load current? |
| A. | 1.96 mA |
| B. | 2 mA |
| C. | 2.04 mA |
| D. | None |
| Answer» B. 2 mA | |
| 392. |
Consider the following statements:The bias stability of an emitter-bias amplifier circuit improves by decreasing the value of RBincreasing the value of REdecreasing the value of RBincreasing the value of RBincreasing the value of RC Which of the above statements are correct? |
| A. | 1 and 2 |
| B. | 2 and 3 |
| C. | 3 and 4 |
| D. | 4 and 5 |
| Answer» B. 2 and 3 | |
| 393. |
Which of the following statements about the matched filter in a communication receiver are correct? Its impulse response depends on the signed shapeIt maximizes the SNR at the detection shape.It produces ISI.It may produce phase error if synchronization is improper. Select the correct answer from the codes given below: |
| A. | 1 and 4 only |
| B. | 1 and 2 only |
| C. | 2, 3 and 4 |
| D. | 1, 2 and 4 |
| Answer» C. 2, 3 and 4 | |
| 394. |
The 4 point Discrete Fourier Transform (DFT) of a discrete time sequence {1, 0, 2, 3} is |
| A. | [0, - 2 + 2j, 2, - 2 - 2j] |
| B. | [2, 2 + 2j, 6, 2 - 2j] |
| C. | [6, 1 - 3j, 2, 1 + 3] |
| D. | [6, - 1 + 3j, 0, - 1 - 3j] |
| Answer» E. | |
| 395. |
Consider the following statements regarding an antenna: It is a transducerIts performance is essentially frequency sensitiveIt is a reciprocal deviceWith increase in its effective aperture area, width of the radiated beam increases. Which of the above statements are correct? |
| A. | 1, 2 and 3 |
| B. | 1, 2 and 4 |
| C. | 2 and 3 only |
| D. | 1 and 4 only |
| Answer» B. 1, 2 and 4 | |
| 396. |
The Vs is given by |
| A. | 8 V |
| B. | 13 V |
| C. | 1 V |
| D. | 4 V |
| Answer» C. 1 V | |
| 397. |
The maximum concentration of the element which can be dissolved in solid silicon at a given temperature is termed as |
| A. | Solid solubility |
| B. | Dissolution coefficient |
| C. | Solidification index |
| D. | Concentration index |
| Answer» C. Solidification index | |
| 398. |
Which of the following are included in the architecture of a computer? Addressing modes, CPUInstruction set, data formatsSecondary memory, operating system Select the correct answer from the codes given below: |
| A. | 1 and 2 |
| B. | 1 and 3 |
| C. | 2 and 3 |
| D. | 3 only |
| Answer» B. 1 and 3 | |
| 399. |
If D, G and η denote the directly, power gain and efficiency of an antenna, then which of the following relation holds : |
| A. | DGη = 1 |
| B. | η = DG |
| C. | D = ηG |
| D. | D = G/η |
| Answer» E. | |
| 400. |
A negative-feedback closed-loop system is supplied to an input 5 V. The system has a forward gain of 1 and a feedback gain of 1 and a feedback gain of 1. What is the output voltage? |
| A. | 1.0 V |
| B. | 1.5 V |
| C. | 2.0 V |
| D. | 2.5 V |
| Answer» E. | |