MCQOPTIONS
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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.
| 1. |
Is the signal x(n) = u(n + 4) – u(n – 4) causal? |
| A. | yes |
| B. | no |
| Answer» C. | |
| 2. |
Is the signal x(t)= eat u(t) causal? |
| A. | yes |
| B. | no |
| Answer» B. no | |
| 3. |
How does Fourier series make it easier to represent periodic signals? |
| A. | harmonically related |
| B. | periodically related |
| C. | sinusoidally related |
| D. | exponentially related |
| Answer» B. periodically related | |
| 4. |
Determine the Time period of: x(t)=3 cos(20t+5)+sin(8t-3). |
| A. | 1/10 sec |
| B. | 1/20 sec |
| C. | 2/5 sec d 2/4 sec |
| Answer» D. | |
| 5. |
Causal systems are |
| A. | anticipative |
| B. | non anticipative |
| C. | for certain cases anticipative |
| D. | for certain cases anticipative and non anticipative |
| Answer» C. for certain cases anticipative | |
| 6. |
Which is the correct Euler expression? |
| A. | exp(2jt) = cos(2t) + jsin(t) |
| B. | exp(2jt) = cos(2t) + jsin(2t) |
| C. | exp(2jt) = cos(2t) + sin(t) |
| D. | exp(2jt) = jcos(2t) + jsin(t) |
| Answer» C. exp(2jt) = cos(2t) + sin(t) | |
| 7. |
Which one of the following is not a ramp function? |
| A. | r(t) = t when t ≥ 0 |
| B. | r(t) = 0 when t < 0 |
| C. | r(t) = ∫u(t)dt when t < 0 |
| D. | r(t) = du(t)⁄dt |
| Answer» E. | |
| 8. |
Fourier series uses which domain representation of signals? |
| A. | time domain representation |
| B. | frequency domain representation |
| C. | both combined |
| D. | neither depends on the situation |
| Answer» C. both combined | |
| 9. |
When we take up design of systems, ideally how do we define the stability of a system? |
| A. | a system is stable, if a bounded input gives a bounded output, for some values of the input |
| B. | a system is unstable, if a bounded input gives a bounded output, for all values of the input |
| C. | a system is stable, if a bounded input gives a bounded output, for all values of the input |
| D. | a system is unstable, if a bounded input gives a bounded output, for some values of the input |
| Answer» D. a system is unstable, if a bounded input gives a bounded output, for some values of the input | |
| 10. |
When two LTI systems with impulse responses ha (t) and hb (t) are cascaded then equivalent response is given by |
| A. | h(t) = ha(t) + hb(t) |
| B. | h(t) = ha(t) – hb(t) |
| C. | h(t) = ha(t) hb(t) |
| D. | h(t) = ha(t) * hb(t) |
| Answer» E. | |
| 11. |
The convolution of a function with an impulse function delayed to an instant 3 in time results in |
| A. | an advance in the function by 3 units in time |
| B. | the function itself |
| C. | a delay in the function by 3 units in time |
| D. | cannot be determined |
| Answer» D. cannot be determined | |
| 12. |
Compute d[n]d[n-1] + d[n-1]d[n-2] for n = 0, 1, 2. |
| A. | 0, 1, 2 |
| B. | 0, 0, 1 |
| C. | 1, 0, 0 |
| D. | 0, 0, 0 |
| Answer» E. | |
| 13. |
A system is said to be defined as non causal, when |
| A. | the output at the present depends on the input at an earlier time |
| B. | the output at the present does not depend on the factor of time at all |
| C. | the output at the present depends on the input at the current time |
| D. | the output at the present depends on the input at a time instant in the future |
| Answer» E. | |
| 14. |
Weighted superposition of time-shifted impulse responses is termed as for discrete-time signals. |
| A. | convolution integral |
| B. | convolution multiple |
| C. | convolution sum |
| D. | convolution |
| Answer» D. convolution | |
| 15. |
A signal is a physical quantity which does not vary with |
| A. | time |
| B. | space |
| C. | independent variables |
| D. | dependent variables |
| Answer» E. | |
| 16. |
Then, y[k] = x[3k-2] is |
| A. | y[k] = 1, for k = 0, 1 and 0 otherwise |
| B. | y[k] = 1, for k = 1 and -1 for k=-1 |
| C. | y[k] = 1, for k = 0, 1 and -1 otherwise |
| D. | y[k] = 1, for k = 0, 1 and 0 otherwise |
| Answer» B. y[k] = 1, for k = 1 and -1 for k=-1 | |
| 17. |
exp[jwn] is periodic |
| A. | for any w |
| B. | for any t |
| C. | for w=2pi*m/n |
| D. | for t = 1/w |
| Answer» D. for t = 1/w | |
| 18. |
The system described by the difference equation y(n) – 2y(n-1) + y(n-2) = X(n) – X(n-1) has y(n) = 0 and n |
| A. | 2 |
| B. | 1 |
| C. | -1 |
| Answer» D. | |
| 19. |
A Discrete signal is said to be even or symmetric if X(-n) is equal to |
| A. | x(n) |
| B. | 0 |
| C. | –x(n) |
| D. | –x(-n) |
| Answer» B. 0 | |
| 20. |
exp(jwt) is periodic |
| A. | for any w |
| B. | for any t |
| C. | for no w |
| D. | for no t |
| Answer» B. for any t | |
| 21. |
Is the following signal an energy signal? x(t) = u(t) – u(t – 1) |
| A. | yes |
| B. | no |
| Answer» B. no | |
| 22. |
The Fourier series for the function f (x) = sin2x is |
| A. | 0.5 + 0.5 sin 2x |
| B. | 0.5 – 0.5 sin 2x |
| C. | 0.5 + 0.5 cos 2x |
| D. | 0.5 – 0.5 cos 2x |
| Answer» E. | |
| 23. |
Determine the power of the signal: x(t) = cos(t). |
| A. | 1/2 |
| B. | 1 c) 3/2 |
| C. | 2 |
| Answer» B. 1 c) 3/2 | |
| 24. |
The convolution of a discrete signal with itself is |
| A. | squaring the signal |
| B. | doubling the signal |
| C. | adding two signals |
| D. | is not possible |
| Answer» B. doubling the signal | |
| 25. |
All causal systems must have the component of |
| A. | memory |
| B. | time invariance |
| C. | stability |
| D. | linearity |
| Answer» B. time invariance | |
| 26. |
Determine the nature of the signal: x(t) = e-0.2t [cosΩt + jsinΩt]. |
| A. | exponentially decaying sinusoidal signal |
| B. | exponentially growing sinusoidal signal |
| C. | sinusoidal signal |
| D. | exponential signal |
| Answer» B. exponentially growing sinusoidal signal | |
| 27. |
A signal is anti-causal if |
| A. | x(t) = 0 for t = 0 |
| B. | x(t) = 1 for t < 0 |
| C. | x(t) = 1 for t > 0 |
| D. | x(t) = 0 for t > 0 |
| Answer» E. | |
| 28. |
Is the signal sin(t) anti-symmetric? |
| A. | yes |
| B. | no |
| Answer» B. no | |
| 29. |
Sum of two periodic signals is a periodic signal when the ratio of their time periods is |
| A. | a rational number |
| B. | an irrational number |
| C. | a complex number |
| D. | an integer |
| Answer» B. an irrational number | |
| 30. |
The range for unit step function for u(t – a), is |
| A. | t < a |
| B. | t ≤ a |
| C. | t = a |
| D. | t ≥ a |
| Answer» E. | |
| 31. |
The most general form of complex exponential function is: |
| A. | eσt |
| B. | eΩt |
| C. | est |
| D. | eat |
| Answer» D. eat | |
| 32. |
The causal continuous system with impulse response should satisfy equation. |
| A. | h(t)=0,t<0 |
| B. | h(t)=0,t>0 |
| C. | h(t)≠0,t<0 |
| D. | h(t)≠0,t≤0 |
| Answer» B. h(t)=0,t>0 | |
| 33. |
For a causal L.T.I. system, the impulse response is 0 for |
| A. | t<0 |
| B. | t=0 |
| C. | t>0 |
| D. | always |
| Answer» B. t=0 | |
| 34. |
For an energy signal |
| A. | e=0 |
| B. | p= ∞ |
| C. | e= ∞ |
| D. | p=0 |
| Answer» E. | |
| 35. |
Defining u(t), r(t) and s(t) in their standard ways, are their derivatives defined at t = 0? |
| A. | yes, yes, no |
| B. | no, yes, no |
| C. | no, no, yes |
| D. | no, no, no |
| Answer» E. | |
| 36. |
A complex exponential signal is a decaying exponential signal when |
| A. | Ω = 0 and σ > 0 |
| B. | Ω = 0 and σ = 0 |
| C. | Ω ≠ 0 and σ < 0 |
| D. | Ω = 0 and σ < 0 |
| Answer» E. | |
| 37. |
Define the fundamental period of the following signal x[n] = exp(2pi*j*n/3) + exp(3*pi*j*n/4)? |
| A. | 8 |
| B. | 12 |
| C. | 18 |
| D. | 24 |
| Answer» E. | |
| 38. |
Impulse response is the output of system due to impulse input applied at time=0? |
| A. | linear |
| B. | time varying |
| C. | time invariant |
| D. | linear and time invariant |
| Answer» E. | |
| 39. |
Determine the odd component of the signal: x(t)=cost+sint. |
| A. | sint |
| B. | 2sint |
| C. | cost |
| D. | 2cost |
| Answer» D. 2cost | |
| 40. |
Most of the signals found in nature are |
| A. | continuous-time and discrete-time |
| B. | continuous-time and digital |
| C. | digital and analog |
| D. | analog and continuous-time |
| Answer» E. | |
| 41. |
The impulse response of discrete-time signal is given by h [n] = u [n+3]. Whether the system is causal or not? |
| A. | causal |
| B. | non-causal |
| C. | insufficient information |
| D. | the system cannot be classified |
| Answer» C. insufficient information | |
| 42. |
The fourier series coefficients of the signal are carried from –T/2 to T/2. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 43. |
If xk = ak and k ≥ 0X(z) = (1 - az-1)-1 with |a| < |z| |
| A. | True |
| B. | False |
| Answer» C. | |
| 44. |
If and k > 0 X(z) = - In (1 - z-1) with 1 < |z| |
| A. | True |
| B. | False |
| Answer» B. False | |
| 45. |
If xk = 2k for k ≤ 0 and = 0 for k > 0 X(z) = 2/(2 - z). |
| A. | True |
| B. | False |
| Answer» B. False | |
| 46. |
For the single rectangular pulse of the given figureF(jω) = [Ad sin (ωd/2)]/(ωd/2). |
| A. | True |
| B. | False |
| Answer» B. False | |
| 47. |
If v(t) = 0 for t < 0 and e-at for t ≥ 0 V(jω) = 1/(a + jω). |
| A. | True |
| B. | False |
| Answer» B. False | |
| 48. |
If xk = 0 for k < 0 and = 2k for k ≥ 0 X(z) = z/(z -2). |
| A. | True |
| B. | False |
| Answer» B. False | |
| 49. |
If f(t) = 1, F(jω) = 2p δ(ω). |
| A. | True |
| B. | False |
| Answer» B. False | |
| 50. |
L [f(t - a)] = F(jω) e-jωa |
| A. | True |
| B. | False |
| Answer» B. False | |