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.
| 251. |
For the signal in the given figure the Fourier transform is 2sinωΤ₁, then the Fourier transform of the signal in the given figure |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» C. C | |
| 252. |
Assertion (A): If a wave v = A1 + A2 sin ωt is applied to a pure capacitor the current wave is:i = A3 sin(ωt + 90°) Reason (R): A capacitor presents infinite impedance to dc. |
| 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 | |
| 253. |
The inverse Fourier transform of δ(t) is |
| A. | ∪(t) |
| B. | 1 |
| C. | δ(t) |
| D. | e^(j2πt) |
| Answer» C. δ(t) | |
| 254. |
The signal define by the equations u(t - a) = 0 for t < a and u(t - a) = 1 for t ≥ 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 | |
| 255. |
Check the following system for causality |
| A. | (1) and (2) |
| B. | (2) and (3) |
| C. | (1) only |
| D. | (1) and (3) |
| Answer» D. (1) and (3) | |
| 256. |
The Laplace transform of sin ωt is |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» C. C | |
| 257. |
Inverse Fourier transform of ∪(ω) is |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» D. D | |
| 258. |
If the region of convergence of x1(n) + x2(n) is 1/3 < |z| < 2/3, then the region of convergence of x1[n] - x2[n] includes |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» E. | |
| 259. |
The following table gives some time functions and the Laplace transforms. Of these correctly matched pairs are |
| A. | 2 and 4 |
| B. | 1 and 4 |
| C. | 3 and 4 |
| D. | 1 and 2 |
| Answer» B. 1 and 4 | |
| 260. |
If f(t) = sgn(t), F(jω) |
| A. | 1 |
| B. | 1/jω |
| C. | 2 |
| D. | 2/jω |
| Answer» E. | |
| 261. |
The z- transform of a systerm is H(z) = z/(z-0.2). If the ROC is |z| < 0.2, then the impluse response of the system is |
| A. | (0.2)ⁿ ∪[n] |
| B. | (0.2)ⁿ ∪[- n - 1] |
| C. | -(0.2)ⁿ ∪[n] |
| D. | -(0.2)ⁿ ∪[- n - 1] |
| Answer» E. | |
| 262. |
A signal x(n) = sin(ω₀n + φ) is the input to a linear time invariant system having a frequency response H(e^(jω)). If the O/P of the system is Ax(n -n₀), then the general form of H(e^(jω)) will be |
| A. | - n₀ω₀ + β for any arbitrary real β |
| B. | - n₀ω₀ + 2πk for any arbitrary integer k |
| C. | n₀ω₀ + 2πk for any arbitrary integer k |
| D. | - n₀ω₀ + φ |
| Answer» C. n₀ω₀ + 2πk for any arbitrary integer k | |
| 263. |
For the signum function sgn(t), F(jω) = |
| A. | 1/jω |
| B. | 2/jω |
| C. | jω |
| D. | 2 jUω |
| Answer» C. jω | |
| 264. |
Initial value theroem for sequence x[n] is |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» D. D | |
| 265. |
The inverse Fourier transform of the function F(ω) = 2/jω is |
| A. | sin ωt |
| B. | cos ωt |
| C. | sgnt |
| D. | u(t) |
| Answer» D. u(t) | |
| 266. |
X and Y are two random variable and Z = X + Y. Let σ²x, σ²y and σ²z be variance of X, Y and Z. Then |
| A. | σ²z = σ²x + σ²y |
| B. | σ²z ≤ σ²x + σ²y |
| C. | σ²z < σ²x + σ²y |
| D. | σ²z > σ²x + σ²y |
| Answer» B. σ²z ≤ σ²x + σ²y | |
| 267. |
Assertion (A): The function δ'(t - b) is equal to 0 for t ≠ bReason (R): A number of impulses spaced from one another form an impulse train. |
| 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 | |
| 268. |
The inverse response of a system h(n) = aⁿ∪(n) what is the condition for the system to be BIBO stable? |
| A. | a is real and +ve |
| B. | a is real and -ve |
| C. | |a| > 1 |
| D. | |a| < 1 |
| Answer» D. |a| < 1 | |
| 269. |
A signal f(t) = cos 10πt + 3 cos 4πt 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. | |
| 270. |
Auto correlation R(t) of a function v(t) is defined as |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» B. B | |
| 271. |
If f(t) is in volts, then F(jω) is in |
| A. | volts |
| B. | volt seconds |
| C. | volts/sec |
| D. | volt-sec² |
| Answer» C. volts/sec | |
| 272. |
If F(jω) is the Fourier transform of f(t) then f(t) = |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» B. B | |
| 273. |
Consider the following as regards cumulative disribution function F(x):1. 0 ≤ F(x) ≤ 12. F(- ∞) = 03. F(∞) = 14. F(x1) ≤ F(x2) If x1 < x2, Out of above which are correct? |
| A. | 1 and 2 only |
| B. | 1, 2 and 3 only |
| C. | 1, 2, 3 and 4 |
| D. | 2 and 4 |
| Answer» D. 2 and 4 | |
| 274. |
To plot frequency spectrum we draw two graphs viz |Fn| versus frequency and φn versus frequency. |
| A. | True |
| B. | False |
| C. | May be True or False |
| D. | can't say |
| Answer» B. False | |
| 275. |
If f1(t) ↔ F1 (jω) and f2(t) ↔ F2(jω), then f1(t)↔ f2(t) |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» D. D | |
| 276. |
Pick out the odd one |
| A. | stochastic variable |
| B. | stochastic function |
| C. | random variable |
| D. | random experiment |
| Answer» E. | |
| 277. |
A system with input x[n] and output y[n] is given as y[n] = (sin 5/6 πn) 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 | |
| 278. |
Consider the following two statements : |
| 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 | |
| 279. |
The tree selected for the formation of state equations contains |
| A. | all voltage sources |
| B. | all capacitors |
| C. | all inductors and current sources |
| D. | all voltage sources and maximum number of capacitors |
| Answer» E. | |
| 280. |
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) | |
| 281. |
Inverse Fourier transform of sgn (ω) is |
| A. | j/πt |
| B. | 1 |
| C. | U(t) |
| D. | 2/jt |
| Answer» B. 1 | |
| 282. |
e^(At) can be expanded as |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» C. C | |
| 283. |
The Fourier transform of f(t) = cos ω₀t is |
| A. | π[δω₀ + δ(- ω₀)] |
| B. | π[δ(ω - ω₀) + δ(ω + ω₀)] |
| C. | π[δω₀ - δ(- ω₀)] |
| D. | π[δ(ω - ω₀) - δ(ω + ω₀)] |
| Answer» C. π[δω₀ - δ(- ω₀)] | |
| 284. |
If f(t) = 1, F(jω) = 2π δ(ω). |
| A. | True |
| B. | False |
| C. | May be True or False |
| D. | can't say |
| Answer» B. False | |
| 285. |
Magnitude Plot of a Composite signal x(t) = e^(2jt) + e^(3jt) is |
| A. | half wave rectified sinusoidal |
| B. | full wave rectified sinusoidal |
| C. | exponentially increasing sinusoidal |
| D. | exponentially decreasing sinusoidal |
| Answer» C. exponentially increasing sinusoidal | |
| 286. |
The joint probability function of two discrete random variable X and Y is given below.Then E(y) is |
| A. | 40/14 |
| B. | 93/14 |
| C. | 8/14 |
| D. | 16/14 |
| Answer» C. 8/14 | |
| 287. |
DTFT (Discrete time Fourier transform) of x[n] = aⁿ∪[n] for -1 < a < + 1. |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» B. B | |
| 288. |
A unit impulse voltage is applied to an inductance at t = 0. The current at t = 0 will be |
| A. | 0 |
| B. | L amperes |
| C. | ∞ |
| D. | I/L amperes |
| Answer» E. | |
| 289. |
The function δ(t - b) is |
| A. | an impulse function |
| B. | a step function originating at t = b |
| C. | an impulse function originating at t = b |
| D. | none of the above |
| Answer» D. none of the above | |
| 290. |
Which of the following represents a stable system? 1. Impulse response decreases exponentially.2. Area within the impulse response in finite.3. Eigen values of the system are positive and real.4. Roots of the characteristic equation of the system are real and positive. Select the answer using the following codes: |
| A. | 1 and 4 |
| B. | 1 and 3 |
| C. | 2, 3 and 4 |
| D. | 1, 2 |
| Answer» E. | |
| 291. |
The data about p the pull required to lift a weight wby a pulley block is given below. The linear law p = a + bw is |
| A. | 3.2 + 0.171 w |
| B. | 2.28 + 0.1879 w |
| C. | 1.2 + 0.25 w |
| D. | 0.6 + 0.3 w |
| Answer» C. 1.2 + 0.25 w | |
| 292. |
If function f(t) has an initial value f(0¯) at t = 0¯, the Laplace transform of d[f(t)]/dt is |
| A. | sF(s) - f(0¯) |
| B. | sF(s) + f(0¯) |
| C. | s²F(s) - f(0¯) |
| D. | s²F(s) + f(0¯) |
| Answer» B. sF(s) + f(0¯) | |
| 293. |
The Fourier series representation of a periodic current (2 + 6√2 cos ωt +√48 sin 2ωt) A. The effective value is |
| A. | (2 + 6 + √24) A |
| B. | 8 A |
| C. | 6 A |
| D. | 2 A |
| Answer» C. 6 A | |
| 294. |
If x[n] = cos[n/2], then the sequence x[n] is |
| A. | periodic |
| B. | non-perodic |
| C. | depends on n |
| D. | none |
| Answer» C. depends on n | |
| 295. |
If H(z) is given by following equation, then system is |
| A. | casual |
| B. | uncasual |
| C. | casual at z = 0.4, 2 |
| D. | uncasual at z = 0.4, z = 2 |
| Answer» B. uncasual | |
| 296. |
The data of speed of train V and resistance to motion R is given below. The 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 | |
| 297. |
The energy E associated with time function f(t) is |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» C. C | |
| 298. |
Assertion (A): If I(s) = 2s+10 / s(s+2) , the final value of i(t) = 10Reason (R): If I(s) = 2s+10 / s(s+2) , the initial value i(t) = 2 |
| 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. | |
| 299. |
The response of a linea, time invariant discrete time system to a unit step input ∪(n) is the unit impulse δ(n). The system response to a ramp input n ∪(n) would be |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» E. | |
| 300. |
Parseval's theorem for energy tells that |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» C. C | |