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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.
| 551. |
The Fourier series representation of a periodic current (2 + 62 cos ωt +48 sin 2ωt) A. The effective value is |
| A. | (2 + 6 + 24) A |
| B. | 0.33333333333333 |
| C. | 0.25 |
| D. | 0.083333333333333 |
| Answer» C. 0.25 | |
| 552. |
If is scaled as an x[n] then ROC changes from `R` to |
| A. | Ra |
| B. | R |
| C. | R/a |
| D. | R + a |
| Answer» C. R/a | |
| 553. |
The effective value of the waveform in the given figure is |
| A. | 5 |
| B. | 2.5 |
| C. | 2.5 |
| D. | 5 |
| Answer» E. | |
| 554. |
The integral of a unit impulse is unit step function. |
| A. | 1 |
| B. | |
| C. | 1 |
| D. | |
| Answer» B. | |
| 555. |
The z- transform of a systerm is If the ROC is |z| < 0.2, then the impluse response of the system is |
| A. | (0.2)n ‚à™[n] |
| B. | (0.2)n ‚à™[- n - 1] |
| C. | -(0.2)n ‚à™[n] |
| D. | -(0.2)n ‚à™[- n - 1] |
| Answer» E. | |
| 556. |
The value of Integral δ(t) sin t dt is equal to |
| A. | zero |
| B. | 1 |
| C. | infinite |
| D. | undefined |
| Answer» B. 1 | |
| 557. |
The eigen values of matrix are |
| A. | 1, 1 |
| B. | - 1, - 1 |
| C. | j, - j |
| D. | 1, - 1 |
| Answer» E. | |
| 558. |
In the given figure the phase angle of Fn is either 0 or Π. |
| A. | 1 |
| B. | |
| C. | 4 cos 100 pt + 8 sin 200 pt |
| D. | 4 cos 100 pt + 8 sin 200 pt + cos 75 pt |
| Answer» B. | |
| 559. |
The property is not valid for basic singularity function is |
| A. | it is even signal |
| B. | convolution of any arbitary function x(t) and an impulse is the original function itself |
| C. | the sum of two impulses at same location is the impulse with the strength equal to the summation of individual strengths. |
| D. | none of these. |
| Answer» E. | |
| 560. |
Highest value of autocorrelation function 100 sin 50 pt is |
| A. | 50 |
| B. | zero |
| C. | 100 |
| D. | 100/p |
| Answer» C. 100 | |
| 561. |
Fourier transform of sgn (t) is |
| A. | |
| B. | |
| Answer» B. | |
| 562. |
The integral of unit step function is a ramp of slope unity. |
| 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» B. y(n) = x(n) - x(n - 1) | |
| 563. |
The theoretical power of white noise is |
| A. | zero |
| B. | finite |
| C. | depend upon frequency of signal |
| D. | infninite |
| Answer» D. infninite | |
| 564. |
If u is input, y is output and a, b are constants, the system y = au + b |
| A. | is linear |
| B. | is nonlinear |
| C. | may be linear or nonlinear dependig on values of a and b |
| D. | may be linear or nonlinear depending on value of u |
| Answer» C. may be linear or nonlinear dependig on values of a and b | |
| 565. |
A system is said to be static system, when present output depend upon |
| A. | present and future |
| B. | past and future |
| C. | a pulse function originating at t = a |
| D. | a step function orginating at t = 0 |
| Answer» B. past and future | |
| 566. |
The Laplace transform of impulse δ(t) is |
| A. | 1 |
| B. | 1/s |
| C. | s |
| D. | 1/s2 |
| Answer» B. 1/s | |
| 567. |
The function A est where s = s + jω represents |
| A. | A phasor rotating in counterclockwise direction at angular frequency ω and whose magnitude increases with t |
| B. | A phasor rotating in clockwise direction at angular frequency ω and whose magnitude increases with t |
| C. | 1 |
| D. | |
| Answer» D. | |
| 568. |
For a Gaussian process, auto-correlation sequence also implies that |
| A. | statistical independence |
| B. | statistical dependence |
| C. | ergodic process |
| D. | all |
| Answer» C. ergodic process | |
| 569. |
The current in a circuit with 10 Ω resistance is i = 3 + 4 sin (100 t + 45°) + 4 sin (300 t + 60°) A. The rms current and power dissipated are |
| A. | 41 A and 410 W |
| B. | 35 A and 350 W |
| C. | 5 A and 250 W |
| D. | 11 A and 1210 W |
| Answer» D. 11 A and 1210 W | |
| 570. |
The derivative of unit step function is |
| A. | unit impulse |
| B. | ramp with slope 1 |
| C. | impulse |
| D. | either (a) or (b) |
| Answer» B. ramp with slope 1 | |
| 571. |
If f(t) is an even function, the coefficients Fn in the exponential form of Fourier series |
| A. | are complex |
| B. | may be real or imaginary |
| C. | 1, 2 and 3 |
| D. | 1 and 2 |
| Answer» B. may be real or imaginary | |
| 572. |
If R(t) is autocorrelation of a waveform v(t) and R(0) is autocorrelation for t = 0, then |
| A. | R(0) > R(t) |
| B. | R(0) ‚â• R(t) |
| C. | R(0) < R(t) |
| D. | R(0) ≤ R(t) |
| Answer» C. R(0) < R(t) | |
| 573. |
In the given figure shows a periodic triangular wave. The Fourier series will have |
| A. | odd cosine terms |
| B. | odd sine terms |
| C. | 1 |
| D. | |
| Answer» C. 1 | |
| 574. |
The signal define by the equations u(t - a) = 0 for t < a and u(t - a) = 1 for t ‚â• a is |
| A. | a unit step function |
| B. | a shifted unit step function orginating at t = a |
| C. | a pulse function |
| D. | none of the above |
| Answer» C. a pulse function | |
| 575. |
Inverse Fourier transform of '1' is |
| A. | U(t) |
| B. | δ(t) |
| C. | '0' |
| D. | infinite |
| Answer» C. '0' | |
| 576. |
Assertion (A): Laplace transform can be used to evalute integrals.Reason (R): Laplace transform can be used to solve 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» C. A is true, R is false | |
| 577. |
If f1 (t) and f2 (f) are two functions of time and a and b are constants, then |
| A. | L [af1(t) + bf2(t)] = aF1(s) + bF2(s) |
| B. | L [af1(t) + bf2(t)] = aF1(s) - bF2(s) |
| C. | L [af1(t) + bf2(t)] =[aF1(s)]/[bF2(s] |
| D. | None of the above |
| Answer» B. L [af1(t) + bf2(t)] = aF1(s) - bF2(s) | |
| 578. |
The Laplace transform of (tn-1) where n is integer is |
| A. | |
| B. | n!/sn |
| C. | absolutely integrable |
| Answer» C. absolutely integrable | |
| 579. |
Assertion (A): The rms value of v = 1 + sin ωt is 1.5Reason (R): If i = I0 + I1m sin ω1t + I3m sin 3ω1t, then |
| 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 | |
| 580. |
Which one is time invariant system? |
| A. | y[n] = x[2n] |
| B. | y[n] = x[n] x[n - 1] |
| C. | y[n] = x[n/2] |
| D. | all |
| Answer» C. y[n] = x[n/2] | |
| 581. |
If F(s) is the Laplace transform of f(t) then Laplace transform of |
| A. | |
| B. | sFU(s) |
| Answer» C. | |
| 582. |
Assertion (A): A non-sinusoidal wave can be expressed in terms of sine waves of different frequencies which are multiples of the frequency of fundamental.Reason (R): If negative half of a complex wave is a reproduction of the positive half, the even harmonics are absent. |
| 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 | |
| 583. |
Energy spectral density is equal to for a signal g(t) |
| A. | |G(f)|2 |
| B. | |g(t)|2 |
| C. | |G(f)|2/Bandwidth |
| Answer» B. |g(t)|2 | |
| 584. |
Assertion (A): The scalling theroem in Laplace transform relates the scale changes in s domain to the consequent changes in t domain.Reason (R): If |
| 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 | |
| 585. |
The integral of a unit impulse is |
| A. | a unit step function |
| B. | a ramp function of slope 1 |
| C. | a pulse function of magnitude 1 |
| D. | none of the above |
| Answer» B. a ramp function of slope 1 | |
| 586. |
Which one condition is true to check the periodically for discrete time signal (where K is any integer, N is period, f0 is frequency of signal) |
| A. | f0 = K/N |
| B. | f0 = K + N |
| C. | f0 = KN |
| D. | f0 = N/K |
| Answer» B. f0 = K + N | |
| 587. |
The signal x(t) = A cos (ω0t + φ) is |
| A. | energy signal |
| B. | power signal |
| C. | energy Power |
| D. | none |
| Answer» C. energy Power | |
| 588. |
Consider z transform of a signal as given belowthen the response will be |
| A. | IIR |
| B. | FIR |
| C. | Depends on value of n |
| D. | Cannot determined |
| Answer» C. Depends on value of n | |
| 589. |
Consider the following sets of values of E, R and C for the circuit in the given figure. 2 V, 1 Ω, 1.25 F1.6 V, 0.8 Ω, 1 F1.6 V, 1 Ω, 0.8 F2 V, 1.25 Ω, 1 F Which of these of values will ensure that the state equation is valid? |
| A. | 1 and 4 |
| B. | 1 and 2 |
| C. | 3 and 4 |
| D. | 2 and 3 |
| Answer» E. | |
| 590. |
The inverse z-transform of X(z) is |
| A. | |
| B. | |
| Answer» B. | |
| 591. |
If for k ‚â• 0 and xk = 0 for k < 0, z transform of the sequence x is |
| A. | |
| B. | |
| Answer» B. | |
| 592. |
A system has poles at 0.01 Hz, 1 Hz and 80 Hz, zeros at 5 Hz, 100 Hz and 200 Hz. The approximate phase of the system response at 20 Hz is |
| A. | -90° |
| B. | 0° |
| C. | 90° |
| D. | -180° |
| Answer» B. 0¬∞ | |
| 593. |
For the wave i = I0 + I1m sin ωt + I3m sin 3ωt, the rms value is |
| A. | I = (I20 + I21m + I23m)0.5 |
| B. | |
| C. | I = 0.707 (I20 + I21m + I23m)0.5 |
| Answer» C. I = 0.707 (I20 + I21m + I23m)0.5 | |
| 594. |
The integral of k δ(t) is |
| A. | a ramp of slope k |
| B. | a ramp of slope 1/k |
| C. | 1 |
| D. | |
| Answer» B. a ramp of slope 1/k | |
| 595. |
If f(t) and F(jω) form a transform pair, then as per symmetry in Fourier transforms |
| A. | F(jt) ↔ 2pf (- ω) |
| B. | F(jt) ↔ pf (ω) |
| Answer» B. F(jt) ‚Üî pf (œâ) | |
| 596. |
(SI - A)-1 = adj(sI - A)/det (sI - A) |
| A. | 1 |
| B. | |
| C. | 1 |
| D. | |
| Answer» B. | |
| 597. |
The value of K in function f(x) = K(x - 1) for K = 1 < x < 4 |
| A. | |
| B. | |
| Answer» C. | |
| 598. |
Assertion (A): L[af1(t) + bf2(t)] = aF1(s) - bF2(s)Reason (R): Initial value theroem enables us to find the value of f(t) at t = 0 directly from F(s) |
| 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» E. | |
| 599. |
Assertion (A): Fourier series can also be written in exponential form.Reason (R): sin (n ωt) and cos (n ωt) can be expressed as sum or difference of exponentials. |
| 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 | |
| 600. |
The impulse response of discrete time system is x[n] = (4)n ‚à™[3 - n], the system is |
| A. | casual |
| B. | stable |
| C. | stable and casual |
| D. | stable and non-casual |
| Answer» E. | |