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MCQOPTIONS
This section includes 902 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.
| 601. |
The triangular wave of the given figure can be written as v(t) = u(t) - tu(t) + (t - 1) u(t - 1) |
| A. | 1 |
| B. | |
| C. | A phasor whose magnitude changes with time |
| D. | A phasor whose frequency is ω |
| Answer» B. | |
| 602. |
A gate function which occurs at t = t0 and lasts for duration T can be written as |
| A. | u (t - t0 - T) |
| B. | u(t - t0) = u(t - t0 - T) |
| C. | u(t - t0) - u(t - t0 - T) |
| D. | u(t - t0) - u(t - t0 + T) |
| Answer» D. u(t - t0) - u(t - t0 + T) | |
| 603. |
A linear system is characterized by H(ω) = Be-2ω2 the system is physically |
| A. | unrealizable |
| B. | realizable |
| C. | depends upon B |
| D. | depends upon constant 2 |
| Answer» B. realizable | |
| 604. |
To plot frequency spectrum we draw two graphs viz |Fn| versus frequency and φn versus frequency. |
| A. | 1 |
| B. | |
| C. | are real |
| D. | are imaginary |
| Answer» B. | |
| 605. |
Choose correct option |
| A. | var (X + Y) = Var (X) + Var (Y) |
| B. | var (X - Y) = Var (X) + Var (Y) |
| C. | var (X + Y) = Var (X) x Var (Y) |
| D. | Both (a) and (b) |
| Answer» E. | |
| 606. |
In the given figure 15.5 show a discrete time system consisting of a unit delay system, a multiplier and a summer, such that y(k) = x(k - 1) + 0.5 x(k). This system |
| A. | is linear |
| B. | is non linear |
| C. | may be linear or non linear depending on value |
| D. | impossible to judge |
| Answer» B. is non linear | |
| 607. |
For formation of state equations, resistance of the circuit |
| A. | should be in tree |
| B. | should be in cotree |
| C. | may be in tree or cotree |
| D. | none of the above |
| Answer» D. none of the above | |
| 608. |
It f(t) is an odd function, the coefficients Fn in the exponential form of Fourier series |
| A. | are real |
| B. | are imaginary |
| C. | are complex |
| D. | may be real or imaginary |
| Answer» C. are complex | |
| 609. |
If a function f(t) is Laplace transformable, then |
| A. | |f(t)| e-σ1t dt < 0 for a real positive σ1 |
| B. | |f(t)| e-σ1t dt < ∞ for a real positive σ1 |
| C. | all cosine terms |
| D. | all sine terms |
| Answer» B. |f(t)| e-œÉ1t dt < ‚àû for a real positive œÉ1 | |
| 610. |
For the differential equation (D3 - D2 + D -1) [y(t)] = 0 the root of auxiliary equation are |
| A. | -j, j, 1 |
| B. | -j, j, 2 |
| C. | 1, 2, j |
| D. | 1, 2, -j |
| Answer» B. -j, j, 2 | |
| 611. |
The Laplace transform of a vlotage across a capacitor is Vc (s) = . If capacitor is 0.5 F, The current through capacitor at t = 0+ is |
| A. | 0 |
| B. | 0.083333333333333 |
| C. | 0.5 A |
| D. | 0.041666666666667 |
| Answer» D. 0.041666666666667 | |
| 612. |
Assertion (A): A half cycle of sine wave can be expressed as sum of sine wave and another sine wave shifted by T/2 where T is the time period.Reason (R): The function u(t - t0) - u(t - t0 - T) is a gate function occuring at t = t0 and of duration T. |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R are correct but R is not correct explanation of A |
| C. | A is true, R is false |
| D. | A is false, R is true |
| Answer» C. A is true, R is false | |
| 613. |
If X(z) = (1 - a)z-1/[(1 - z-1)(1 - az-1)] and 1 < |z|, the final value of xk is |
| A. | 0 |
| B. | 1 |
| C. | ‚àû |
| D. | 2 |
| Answer» C. ‚àû | |
| 614. |
A system with input x[n] and output y[n] is given as y[n] = (sin 5/6 pn) x(n) The system is |
| A. | linear, stable and invertible |
| B. | non-linear, stable and non-invertible |
| C. | linear stable, non invertible |
| D. | linear, unstable, invertible |
| Answer» D. linear, unstable, invertible | |
| 615. |
A trigonometric series has |
| A. | single sided spectra |
| B. | zero |
| C. | sync function |
| D. | undefined |
| Answer» B. zero | |
| 616. |
The data of speed of train V and resistance to motion R isThe law R = a + bV2 is of the form |
| A. | 6.7 + 0.0092 V2 |
| B. | 3 + 0.001 V2 |
| C. | 3.2 + 0.0012 V2 |
| D. | 5.2 + 0.006 V2 |
| Answer» B. 3 + 0.001 V2 | |
| 617. |
Highest value of Autocorrelation of a function 100 cos 50 pt is |
| A. | zero |
| B. | 100/p |
| C. | 1/sn |
| D. | (n - 1)!/sn |
| Answer» C. 1/sn | |
| 618. |
L[c1f1(t) + c2f2(t)] = |
| A. | c1 F1 (jω) + c2 F2(jω) |
| B. | c1 F1 (jω) - c2 F2(jω) |
| C. | c1 F1 (jω) + c2 F2(jω) + c1c2 |
| D. | c1 F1 (jω) + c2 F2(jω) + c1/c2 |
| Answer» B. c1 F1 (jœâ) - c2 F2(jœâ) | |
| 619. |
Assertion (A): If Reason (R): |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R are correct but R is not correct explanation of A |
| C. | A is true, R is false |
| D. | A is false, R is true |
| Answer» B. Both A and R are correct but R is not correct explanation of A | |
| 620. |
The signal is |
| A. | periodic for t > 0 |
| B. | non-periodic |
| C. | periodic for t < 0 |
| D. | depends on t |
| Answer» C. periodic for t < 0 | |
| 621. |
The waveform shown in the given Figure can be written as |
| A. | v(t) = u(t - 1) + u(t - 2) + u(t - 3) + u(t -4) |
| B. | v(t) = u(t - 1) + u(t - 2) + u(t - 3) + u(t -4) - u(t - 5) |
| C. | v(t) = u(t - 1) + u(t - 2) + u(t - 3) + u(t -4) - 4u(t - 5) |
| D. | v(t) = u(t - 1) + u(t - 2) + u(t - 3) + u(t -4) + 4u(t - 5) |
| Answer» D. v(t) = u(t - 1) + u(t - 2) + u(t - 3) + u(t -4) + 4u(t - 5) | |
| 622. |
Assertion (A): Transient analysis uses Laplace transformation.Reason (R): Laplace transform method is suitable for solution of integro differential equations. |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R are correct but R is not correct explanation of A |
| C. | A is true, R is false |
| D. | A is false, R is true |
| Answer» B. Both A and R are correct but R is not correct explanation of A | |
| 623. |
In plotting line spectrum |
| A. | a graph of complex number Fn versus frequency is plotted |
| B. | a graph of |Fn| versus frequency is plotted |
| C. | a graph of the angle of Fn versus frequency is plotted |
| D. | two graphs viz |Fn| versus frequency and the phase angle of Fn versus frequency are plotted |
| Answer» E. | |
| 624. |
If the sequence |xn|1/n converges, then the series converages absolutely is |
| A. | Ratio test |
| B. | Root test |
| C. | Convergence test |
| D. | Divergence test |
| Answer» C. Convergence test | |
| 625. |
If a function f(t) is an odd, function, its Fourier series |
| A. | contains only sine terms |
| B. | contains only cosine terms |
| C. | contains a constant and sine terms |
| D. | contains a constant and cosine |
| Answer» B. contains only cosine terms | |
| 626. |
The integral of a unit step function is |
| A. | a unit impulse function |
| B. | a unit pulse function |
| C. | a ramp function of slope 1 |
| D. | none of the above |
| Answer» D. none of the above | |
| 627. |
In a complex wave, the negative half of the wave is a reproduction of the positive half wave. Then |
| A. | the wave contains only fundamental and third harmonic |
| B. | the wave does not contain even harmonics |
| C. | the wave does not contain odd harmonics |
| D. | the wave does not contain triple harmonics |
| Answer» C. the wave does not contain odd harmonics | |
| 628. |
A signal f(t) = cos 10pt + 3 cos 4pt is instantaneously sampled. The maximum allowable value of sampling interval Ts in sec is |
| A. | 1 / 4 sec |
| B. | 1 / 8 sec |
| C. | 1 / 8p sec |
| D. | 1 / 10 sec |
| Answer» E. | |
| 629. |
FIR digital filter having __________ stability than FIR filter. |
| A. | good stability |
| B. | poor stability |
| C. | stability not guarnteed |
| D. | poor stability |
| Answer» B. poor stability | |
| 630. |
A voltage wave containing 10% third harmonic is applied to a scries R-L circuit. The percentage third harmonic content in the current wave will be |
| A. | more than 10% |
| B. | 10% or less than 10% |
| C. | less than 10% |
| D. | 10% or more or less |
| Answer» D. 10% or more or less | |
| 631. |
Which one of the systems described by the following I/P - O/P relations is time invariant |
| A. | y(n) = n x(n) |
| B. | y(n) = x(n) - x(n - 1) |
| C. | y(n) = x(- n) |
| D. | y(n) = x(n) cos 2pf0n |
| Answer» C. y(n) = x(- n) | |
| 632. |
If £ f(t) = F(jω), then |
| A. | (jω)n F(jω) |
| B. | F(jω)/(jω)n |
| C. | (jω)n-1 F(jω) |
| D. | (b) F(jω)/(jω)n-1 |
| Answer» B. F(jœâ)/(jœâ)n | |
| 633. |
A 1 kHz sinusoidal signal is ideally sampled at 1500 samples/sec and the sampled signal is passed through an ideal low pass filter with cut off frequency 800 Hz. The output signal has the frequency. |
| A. | 0 Hz |
| B. | 0.75 kHz |
| C. | 0.5 kHz |
| D. | 0.25 kHz |
| Answer» D. 0.25 kHz | |
| 634. |
In RLC circuits the state variables generally selected are |
| A. | voltages across capacitors |
| B. | currents through resistances and voltages across capacitors |
| C. | currents through resistances and capacitances |
| D. | currents through inductances and voltages across capacitances |
| Answer» E. | |
| 635. |
Auto correlation for t = 0 is equal to |
| A. | average power S of waveform |
| B. | square of average power S of waveform |
| C. | half of average power S of waveform |
| D. | square root of average power S of waveform |
| Answer» B. square of average power S of waveform | |
| 636. |
If then the sequence x[n] is |
| A. | periodic |
| B. | non-perodic |
| C. | depends on n |
| D. | none |
| Answer» C. depends on n | |
| 637. |
If xk = ak and k < 0X(z) = - (1 - az-1)-1 with |z| < |a| |
| A. | 1 |
| B. | |
| Answer» B. | |
| 638. |
The output of a linear system for any input can be computed in which of the following ways? |
| A. | Only by summation of inpulse response by convolution integral |
| B. | Only by summation of step response by superposition integral |
| C. | Neither a nor b |
| D. | Either (a) or (b) |
| Answer» E. | |
| 639. |
Fourier transform of non periodic DT signal is |
| A. | aperiodic |
| B. | Periodic |
| C. | both a and b |
| D. | None of these |
| Answer» C. both a and b | |
| 640. |
The function δ' (t-b) is |
| A. | a step function originating at t = b |
| B. | an impulse function originating at t = b |
| C. | a unit doublet originating at = t - b |
| D. | none of the above |
| Answer» D. none of the above | |
| 641. |
If f(t) ↔ F(jω), f(- t) ↔ |
| A. | #NAME? |
| B. | F(- jω) |
| C. | F(jω) |
| D. | 0.5 F(jω) |
| Answer» C. F(jœâ) | |
| 642. |
Assertion (A): In the curve , a high value of h indicate a high peak and rapid fall in the curve.Reason (R): If the number of ways in an event may result can be analysed into a successes and b failures, each equally likely to occur, the probability of success in a single trial is |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R are correct but R is not correct explanation of A |
| C. | A is true, R is false |
| D. | A is false, R is true |
| Answer» C. A is true, R is false | |
| 643. |
If ROC of x[n] is R1 then ROC of an x[n] is |
| A. | R1a |
| B. | R1/a |
| C. | a/R1 |
| D. | R1 + a |
| Answer» C. a/R1 | |
| 644. |
A pulse function having magnitude E and duration from t = 0 to t = a can be represented as |
| A. | sum of two pulse functions |
| B. | difference of two pulse functions |
| C. | difference of two step functions each of magnitude E and one originating at t = 0 and the other at t = a |
| D. | none of the above |
| Answer» D. none of the above | |
| 645. |
The output y(t) of a linear time invariant system is related to its input x(t) by the following equation y(t) = 0.5x(t - td + 1) + x(t - td) + 0.5 x(t - td + 7). The filter transfer function H(ω) of such a system is given by |
| A. | (1 + cos ωt)e-jωt d |
| B. | (1 + 0.5 cos ωt)e-jωt d |
| C. | (1 + cos ωt)ejωt d |
| D. | (1 - 0.5 cos ωt)e-jωt d |
| Answer» B. (1 + 0.5 cos œât)e-jœât d | |
| 646. |
A signal is x + f(t) where x is constant and f(t) is a power signal with zero mean value. The power of the signal is |
| A. | x2 |
| B. | x2 + f2(t) |
| C. | more than x2 + f2(t) |
| D. | less than x2 + f2(t) |
| Answer» C. more than x2 + f2(t) | |
| 647. |
The units of the spectrum obtained be Fourier transforming the covariance function of a stationery Stochastic Process is |
| A. | Power per Hz |
| B. | energy per Hz |
| C. | Power per sec |
| D. | Energy per second |
| Answer» C. Power per sec | |
| 648. |
The impulse response of the DT - LTI system is given below       Check whether the system is StableCasualDynamic. |
| A. | 1 and 2 |
| B. | 2 and 3 |
| C. | 1 and 3 |
| D. | 1, 2 and 3 |
| Answer» E. | |
| 649. |
A voltage v = 100 sin ωt + 10 sin 5 ωt is applied to a pure capacitor having capacitance of 1 μF. If ω = 314 rad/sec, the current through the capacitor is |
| A. | 0.0314 cos 314 t + 0.0157 cos 1570 t |
| B. | 0.0314 sin 314 t + 0.0157 sin 1570 t |
| C. | 0.0314 cos 314 t + 0.0314 cos 1570 t |
| D. | 0.0157 cos 314 t + 0.0157 cos 1570 t |
| Answer» B. 0.0314 sin 314 t + 0.0157 sin 1570 t | |
| 650. |
A casual system having the transfer function is excited with 10 ‚à™(t). The time at which the output reaches 99% of its steady-state value is |
| A. | 2.7 sec |
| B. | 2.5 sec |
| C. | 2.3 sec |
| D. | 2.1 sec |
| Answer» D. 2.1 sec | |