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All Electronics & Telecommunication MCQs

Browse Electronics & Telecommunication Engineering MCQs with four options, hidden answers, concise explanations and references where available. Questions are organized in pages of up to 100 for focused practice.

Question 504
Communication SystemsInformation Theory

For a binary symmetric channel with crossover probability p=0, its capacity is?

  • A0 bit per channel use
  • B0.5 bit per channel use
  • C1 bit per channel use
  • D2 bits per channel use
Report an error
Correct Answer: C. 1 bit per channel use
Explanation: With no crossover errors, a binary input can convey one bit of information per channel use.
Reference: Standard communication systems: information theory
Question 509
Signals & SystemsSignal Fundamentals

A signal that is defined for every value of continuous time t is called a?

  • AContinuous-time signal
  • BDiscrete-time signal
  • CBinary code only
  • DQuantized sequence only
Report an error
Correct Answer: A. Continuous-time signal
Explanation: A continuous-time signal x(t) is defined over a continuous range of the independent variable t.
Reference: Standard signals and systems: signal fundamentals
Question 510
Signals & SystemsSignal Fundamentals

A discrete-time signal is commonly represented as?

  • Ax(t) only
  • Bx[n]
  • CX(s) only
  • DV/Hz
Report an error
Correct Answer: B. x[n]
Explanation: A discrete-time signal is represented as a sequence x[n], where n is an integer index.
Reference: Standard signals and systems: signal fundamentals
Question 512
Signals & SystemsElementary Signals

The continuous-time unit impulse delta(t) has unit?

  • AAmplitude at all times
  • BArea
  • CPeriod
  • DAverage power
Report an error
Correct Answer: B. Area
Explanation: The Dirac impulse is characterized by zero value away from t=0 and unit area over an interval containing the origin.
Reference: Standard signals and systems: elementary signals
Question 514
Signals & SystemsElementary Signals

The integral of delta(t) from minus infinity to t is?

  • Au(t)
  • Bdelta(t)
  • Ct
  • D0 for every t
Report an error
Correct Answer: A. u(t)
Explanation: Integrating the unit impulse from -infinity up to t produces the unit-step function.
Reference: Standard signals and systems: elementary signals
Question 517
Signals & SystemsPeriodic Signals

The fundamental period of x(t)=cos(20pi t) is?

  • A0.01 s
  • B0.05 s
  • C0.1 s
  • D0.2 s
Report an error
Correct Answer: C. 0.1 s
Explanation: Here omega=20pi rad/s, so f=10 Hz and T=1/f=0.1 s.
Reference: Standard signals and systems: periodic signals
Question 518
Signals & SystemsPeriodic Signals

A continuous-time sinusoidal signal is periodic when its angular frequency is?

  • ANonzero; every single continuous-time sinusoid with fixed nonzero frequency is periodic
  • BAn integer only
  • CLess than 1 rad/s only
  • DExactly pi rad/s only
Report an error
Correct Answer: A. Nonzero; every single continuous-time sinusoid with fixed nonzero frequency is periodic
Explanation: A single continuous-time sinusoid cos(omega0 t+phi) with fixed nonzero omega0 has period 2pi/|omega0|.
Reference: Standard signals and systems: periodic signals
Question 519
Signals & SystemsPeriodic Signals

A discrete-time sinusoid x[n]=cos(omega0 n) is periodic only if?

  • Aomega0/(2pi) is rational
  • Bomega0/(2pi) is irrational
  • Comega0=1 always
  • DIts amplitude is less than one
Report an error
Correct Answer: A. omega0/(2pi) is rational
Explanation: A discrete-time sinusoid is periodic if there exist integers N>0 and k such that omega0 N=2pi k, equivalently omega0/(2pi) is rational.
Reference: Standard signals and systems: periodic signals
Question 521
Signals & SystemsSignal Classification

A signal x(t) is even if it satisfies?

  • Ax(-t)=x(t)
  • Bx(-t)=-x(t)
  • Cx(t+T)=0
  • Dx(t)=delta(t) only
Report an error
Correct Answer: A. x(-t)=x(t)
Explanation: An even signal is symmetric about the vertical axis and obeys x(-t)=x(t).
Reference: Standard signals and systems: signal classification
Question 522
Signals & SystemsSignal Classification

A signal x(t) is odd if it satisfies?

  • Ax(-t)=x(t)
  • Bx(-t)=-x(t)
  • Cx(t)=1 for all t
  • Dx(t)=x(t-1)
Report an error
Correct Answer: B. x(-t)=-x(t)
Explanation: An odd signal has origin symmetry and obeys x(-t)=-x(t).
Reference: Standard signals and systems: signal classification
Question 524
Signals & SystemsSignal Classification

The odd part of a signal x(t) is?

  • A[x(t)+x(-t)]/2
  • B[x(t)-x(-t)]/2
  • Cx(-t) only
  • Dx(t)/2 only
Report an error
Correct Answer: B. [x(t)-x(-t)]/2
Explanation: The odd component is xo(t)=1/2[x(t)-x(-t)].
Reference: Standard signals and systems: signal classification
Question 526
Signals & SystemsSignal Transformations

The signal x(2t) is, relative to x(t),?

  • ATime-expanded by 2
  • BTime-compressed by 2
  • CDelayed by 2 s
  • DAmplitude-scaled by 2 only
Report an error
Correct Answer: B. Time-compressed by 2
Explanation: Replacing t by 2t compresses the time axis by a factor of 2.
Reference: Standard signals and systems: signal transformations
Question 527
Signals & SystemsSignal Transformations

The signal x(t/2) is, relative to x(t),?

  • ATime-compressed by 2
  • BTime-expanded by 2
  • CTime-reversed
  • DDifferentiated
Report an error
Correct Answer: B. Time-expanded by 2
Explanation: Replacing t by t/2 expands the time axis by a factor of 2.
Reference: Standard signals and systems: signal transformations
Question 528
Signals & SystemsSignal Transformations

The transformation x(-t) represents?

  • AAmplitude inversion
  • BTime reversal
  • CTime delay
  • DIntegration
Report an error
Correct Answer: B. Time reversal
Explanation: Changing t to -t reflects the signal about t=0, which is time reversal.
Reference: Standard signals and systems: signal transformations
Question 529
Signals & SystemsEnergy & Power Signals

A finite-energy signal has energy E that is?

  • AFinite and nonzero, with zero average power
  • BInfinite with finite average power
  • CAlways equal to one
  • DZero for every nonzero signal
Report an error
Correct Answer: A. Finite and nonzero, with zero average power
Explanation: For the usual energy/power classification, an energy signal has 0<E<infinity and average power equal to zero.
Reference: Standard signals and systems: energy & power signals
Question 530
Signals & SystemsEnergy & Power Signals

A nonzero periodic signal with finite average power is generally classified as a?

  • APower signal
  • BEnergy signal with finite nonzero energy
  • CNeither under all conditions
  • DImpulse only
Report an error
Correct Answer: A. Power signal
Explanation: A typical nonzero periodic signal has infinite total energy but finite nonzero average power, so it is a power signal.
Reference: Standard signals and systems: energy & power signals
Question 531
Signals & SystemsEnergy & Power Signals

The total energy of x(t)=e^(-t)u(t) is?

  • A1/4
  • B1/2
  • C1
  • D2
Report an error
Correct Answer: B. 1/2
Explanation: E=∫0^infinity |e^-t|^2 dt=∫0^infinity e^-2t dt=1/2.
Reference: Standard signals and systems: energy & power signals
Question 532
Signals & SystemsSystem Properties

A system is linear if it satisfies the principle of?

  • ASuperposition
  • BAliasing
  • CQuantization
  • DModulation only
Report an error
Correct Answer: A. Superposition
Explanation: Linearity requires additivity and homogeneity, together expressed by the superposition principle.
Reference: Standard signals and systems: system properties
Question 533
Signals & SystemsSystem Properties

A system is time-invariant if?

  • AA time shift of the input produces the same time shift of the output
  • BIts output never changes with time
  • CIt has no memory under all conditions
  • DIts input must be periodic
Report an error
Correct Answer: A. A time shift of the input produces the same time shift of the output
Explanation: For a time-invariant system, delaying the input by t0 delays the corresponding output by the same amount without otherwise changing it.
Reference: Standard signals and systems: system properties
Question 534
Signals & SystemsSystem Properties

A system is causal if its output at any time depends only on?

  • AFuture input values
  • BPresent and past input values
  • CFuture output values only
  • DThe input at t=infinity
Report an error
Correct Answer: B. Present and past input values
Explanation: A causal system cannot depend on future input values; its output may depend on present and past inputs.
Reference: Standard signals and systems: system properties
Question 535
Signals & SystemsSystem Properties

Which system is memoryless?

  • Ay(t)=x(t-2)
  • By(t)=x(t)+x(t-1)
  • Cy(t)=3x(t)
  • Dy(t)=integral from -infinity to t of x(tau)d tau
Report an error
Correct Answer: C. y(t)=3x(t)
Explanation: A memoryless system output at time t depends only on the input at that same time.
Reference: Standard signals and systems: system properties
Question 536
Signals & SystemsSystem Properties

The continuous-time system y(t)=x(t-1) is?

  • ANoncausal
  • BCausal with memory
  • CMemoryless and causal
  • DUnstable for every input
Report an error
Correct Answer: B. Causal with memory
Explanation: It depends on a past input value, so it is causal and has memory.
Reference: Standard signals and systems: system properties
Question 537
Signals & SystemsSystem Properties

A system is BIBO stable if every bounded input produces?

  • AA bounded output
  • BAn unbounded output
  • CZero output only
  • DA periodic output only
Report an error
Correct Answer: A. A bounded output
Explanation: BIBO means bounded-input bounded-output stability.
Reference: Standard signals and systems: system properties
Question 538
Signals & SystemsLTI Systems

For a continuous-time LTI system, BIBO stability requires?

  • AIntegral of |h(t)| over all time is finite
  • Bh(t) must be periodic
  • Ch(t) must be odd
  • DIntegral of h(t) must always be zero
Report an error
Correct Answer: A. Integral of |h(t)| over all time is finite
Explanation: A continuous-time LTI system is BIBO stable if its impulse response is absolutely integrable.
Reference: Standard signals and systems: lti systems
Question 541
Signals & SystemsConvolution

Continuous-time convolution is?

  • AIntegral x(tau)h(t-tau)d tau over all tau
  • BIntegral x(t)h(t)dt only
  • Cx(t)+h(t)
  • Dx(t)/h(t)
Report an error
Correct Answer: A. Integral x(tau)h(t-tau)d tau over all tau
Explanation: Continuous-time convolution integrates x(tau)h(t-tau) over all tau.
Reference: Standard signals and systems: convolution
Question 542
Signals & SystemsConvolution

Which is a property of convolution?

  • Ax*h=h*x
  • Bx*h=x-h
  • CIt is never associative
  • DIt requires x=h
Report an error
Correct Answer: A. x*h=h*x
Explanation: Convolution is commutative.
Reference: Standard signals and systems: convolution
Question 543
Signals & SystemsConvolution

Convolution with the unit impulse gives?

  • A0
  • Bx(t)
  • C1
  • Ddx(t)/dt
Report an error
Correct Answer: B. x(t)
Explanation: The unit impulse is the identity for convolution.
Reference: Standard signals and systems: convolution
Question 544
Signals & SystemsConvolution

x(t)*delta(t-t0) equals?

  • Ax(t+t0)
  • Bx(t-t0)
  • Cdelta(t)
  • Dx(t0) only
Report an error
Correct Answer: B. x(t-t0)
Explanation: A shifted impulse shifts the convolved signal by the same amount.
Reference: Standard signals and systems: convolution
Question 547
Signals & SystemsDiscrete-Time LTI

Discrete-time convolution uses?

  • AA summation over an integer index
  • BOnly a continuous integral
  • CMatrix inversion always
  • DDifferentiation only
Report an error
Correct Answer: A. A summation over an integer index
Explanation: y[n]=sum x[k]h[n-k].
Reference: Standard signals and systems: discrete-time lti
Question 548
Signals & SystemsDiscrete-Time LTI

Discrete-time LTI BIBO stability requires?

  • ASum of |h[n]| over all n is finite
  • Bh[n]=n
  • Ch[n] periodic
  • Dh[0]=0
Report an error
Correct Answer: A. Sum of |h[n]| over all n is finite
Explanation: The impulse response must be absolutely summable.
Reference: Standard signals and systems: discrete-time lti
Question 550
Signals & SystemsFourier Series

Fourier series is primarily used to represent?

  • APeriodic signals
  • BOnly nonperiodic impulses
  • COnly random noise
  • DDC circuits only
Report an error
Correct Answer: A. Periodic signals
Explanation: Fourier series represents periodic signals using harmonically related components.
Reference: Standard signals and systems: fourier series
Question 553
Signals & SystemsFourier Series

Fourier-series harmonic frequencies are?

  • AInteger multiples of the fundamental
  • BAlways irrational multiples
  • CAlways lower than fundamental
  • DIndependent of fundamental
Report an error
Correct Answer: A. Integer multiples of the fundamental
Explanation: The kth harmonic is k times the fundamental frequency.
Reference: Standard signals and systems: fourier series
Question 556
Signals & SystemsFourier Series

Parseval’s relation connects average power with?

  • ASquared magnitudes of Fourier-series coefficients
  • BOnly maximum amplitude
  • COnly fundamental period
  • DDerivative at t=0
Report an error
Correct Answer: A. Squared magnitudes of Fourier-series coefficients
Explanation: Parseval expresses signal power through the squared Fourier coefficient magnitudes.
Reference: Standard signals and systems: fourier series
Question 557
Signals & SystemsFourier Series

A standard symmetric 50% duty-cycle square wave contains?

  • AOnly odd harmonics
  • BOnly even harmonics
  • CNo harmonics
  • DOnly second harmonic
Report an error
Correct Answer: A. Only odd harmonics
Explanation: Its even harmonics vanish due to symmetry.
Reference: Standard signals and systems: fourier series
Question 559
Signals & SystemsFourier Transform

The continuous-time Fourier transform X(jω) of x(t) is defined as?

  • A∫x(t)e^(-jωt)dt over all time
  • B∫x(t)e^(jωt)dt from 0 to 1
  • Cx(t)e^(-jωt)
  • Ddx(t)/dt
Report an error
Correct Answer: A. ∫x(t)e^(-jωt)dt over all time
Explanation: The CTFT analysis equation is X(jω)=∫ from -∞ to ∞ x(t)e^(-jωt)dt.
Reference: Standard signals and systems: fourier transform
Question 561
Signals & SystemsFourier Transform

The Fourier transform of delta(t-t0) is?

  • Ae^(-jωt0)
  • Be^(jωt0)
  • Cdelta(ω-t0)
  • D1/(jω)
Report an error
Correct Answer: A. e^(-jωt0)
Explanation: The shifted impulse property gives delta(t-t0) ↔ e^(-jωt0).
Reference: Standard signals and systems: fourier transform
Question 562
Signals & SystemsFourier Transform

If x(t) ↔ X(jω), then x(t-t0) has Fourier transform?

  • AX(jω)e^(-jωt0)
  • BX(jω)e^(jωt0)
  • CX(j(ω-t0))
  • Dt0X(jω)
Report an error
Correct Answer: A. X(jω)e^(-jωt0)
Explanation: A time delay t0 introduces the linear phase factor e^(-jωt0).
Reference: Standard signals and systems: fourier transform
Question 564
Signals & SystemsFourier Transform

Differentiation in time corresponds in the Fourier domain to?

  • ADivision by jω
  • BMultiplication by jω
  • CTime reversal only
  • DMultiplication by t
Report an error
Correct Answer: B. Multiplication by jω
Explanation: If x(t) ↔ X(jω), then dx(t)/dt ↔ jωX(jω), under standard conditions.
Reference: Standard signals and systems: fourier transform
Question 566
Signals & SystemsFourier Transform

Parseval’s relation for the Fourier transform connects signal energy with?

  • AIntegral of |X(jω)|² in frequency
  • BOnly X(0)
  • COnly signal period
  • DMaximum signal amplitude only
Report an error
Correct Answer: A. Integral of |X(jω)|² in frequency
Explanation: Parseval's relation expresses time-domain energy equivalently in terms of the integral of spectral magnitude squared, with the appropriate 1/(2π) factor.
Reference: Standard signals and systems: fourier transform
Question 567
Signals & SystemsLaplace Transform

The bilateral Laplace transform of x(t) is?

  • A∫x(t)e^(-st)dt over all time
  • B∫x(t)e^(st)dt from 0 to 1
  • Cx(t)/s
  • Ddx(t)/dt only
Report an error
Correct Answer: A. ∫x(t)e^(-st)dt over all time
Explanation: The bilateral Laplace transform is X(s)=∫ from -∞ to ∞ x(t)e^(-st)dt.
Reference: Standard signals and systems: laplace transform
Question 572
Signals & SystemsLaplace Transform

For a causal rational LTI system, the ROC of H(s) lies?

  • ATo the right of the rightmost pole
  • BTo the left of the leftmost pole
  • COnly between every pair of poles
  • DExactly on the jω-axis
Report an error
Correct Answer: A. To the right of the rightmost pole
Explanation: A causal rational impulse response is right-sided, so its ROC is to the right of the rightmost pole.
Reference: Standard signals and systems: laplace transform
Question 573
Signals & SystemsLaplace Transform

A causal rational continuous-time LTI system is BIBO stable if all its poles lie?

  • AStrictly in the left half of the s-plane
  • BStrictly in the right half-plane
  • COnly on the jω-axis
  • DAt the origin only
Report an error
Correct Answer: A. Strictly in the left half of the s-plane
Explanation: For a causal rational system, BIBO stability requires the jω-axis to lie in the ROC, which means all poles must be strictly in the left half-plane.
Reference: Standard signals and systems: laplace transform
Question 574
Signals & SystemsZ-Transform

The bilateral Z-transform of x[n] is defined as?

  • AΣ x[n]z^(-n) over all integer n
  • BΣ x[n]z^n for n=0 only
  • Cx[n]/z
  • Ddx[n]/dn
Report an error
Correct Answer: A. Σ x[n]z^(-n) over all integer n
Explanation: The bilateral Z-transform is X(z)=Σ from n=-∞ to ∞ x[n]z^(-n).
Reference: Standard signals and systems: z-transform
Question 575
Signals & SystemsZ-Transform

The Z-transform of a^n u[n] is?

  • A1/(1-az^-1), ROC |z|>|a|
  • B1/(1+az^-1), ROC |z|<|a|
  • Cz-a, all z
  • Da/(z+1), all z
Report an error
Correct Answer: A. 1/(1-az^-1), ROC |z|>|a|
Explanation: For the right-sided sequence a^n u[n], the geometric series gives X(z)=1/(1-az^-1) with ROC |z|>|a|.
Reference: Standard signals and systems: z-transform
Question 576
Signals & SystemsZ-Transform

For a right-sided sequence a^n u[n], the ROC is?

  • A|z|>|a|
  • B|z|<|a|
  • C|z|=|a| only
  • Dz=a only
Report an error
Correct Answer: A. |z|>|a|
Explanation: Convergence of the geometric series requires |az^-1||a|.
Reference: Standard signals and systems: z-transform
Question 577
Signals & SystemsZ-Transform

For a causal rational discrete-time LTI system, the ROC of H(z) is generally?

  • AOutside the outermost pole
  • BInside the innermost pole
  • COnly on the unit circle
  • DBetween zero and every pole
Report an error
Correct Answer: A. Outside the outermost pole
Explanation: A causal rational impulse response is right-sided, so its ROC extends outward from the outermost pole to infinity.
Reference: Standard signals and systems: z-transform
Question 578
Signals & SystemsZ-Transform

A causal rational discrete-time LTI system is BIBO stable when all its poles are?

  • AStrictly inside the unit circle
  • BStrictly outside the unit circle
  • CExactly on the unit circle
  • DAt z=1 only
Report an error
Correct Answer: A. Strictly inside the unit circle
Explanation: For a causal rational system to be stable, the unit circle must lie in the ROC; therefore all poles must lie strictly inside it.
Reference: Standard signals and systems: z-transform
Question 582
Signals & SystemsSampling

Ideal reconstruction of a properly sampled band-limited signal is theoretically performed using a?

  • AIdeal low-pass reconstruction filter
  • BHigh-pass differentiator only
  • CRectifier
  • DLimiter only
Report an error
Correct Answer: A. Ideal low-pass reconstruction filter
Explanation: After ideal impulse-train sampling above the Nyquist rate, an ideal low-pass filter can select the original baseband spectral replica.
Reference: Standard signals and systems: sampling
Question 588
Signals & SystemsStability

A causal rational continuous-time system has poles at -2 and +1. It is BIBO stable?

  • AYes, because one pole is negative
  • BNo, because a pole lies in the right half-plane
  • CYes, because it is causal
  • DAlways stable if rational
Report an error
Correct Answer: B. No, because a pole lies in the right half-plane
Explanation: For a causal rational CT system, all poles must lie strictly in the left half-plane for BIBO stability.
Reference: Standard signals and systems: stability
Question 590
Signals & SystemsStability

A causal discrete-time system has a pole at z=1.2. Its BIBO stability is?

  • AStable
  • BUnstable
  • CMarginally stable in every sense
  • DIndependent of pole location
Report an error
Correct Answer: B. Unstable
Explanation: For a causal rational DT system, a pole outside the unit circle prevents the unit circle from being in the ROC, so it is not BIBO stable.
Reference: Standard signals and systems: stability
Question 591
Signals & SystemsZ-Transform

If h[n]=(0.5)^n u[n], H(z) is?

  • A1/(1-0.5z^-1)
  • B1/(1+0.5z^-1)
  • Cz^-1/0.5
  • D1-0.5z^-1
Report an error
Correct Answer: A. 1/(1-0.5z^-1)
Explanation: The Z-transform of a^n u[n] is 1/(1-az^-1), with |z|>|a|.
Reference: Standard signals and systems: z-transform
Question 595
Signals & SystemsFrequency Response

If an LTI system has H(jω)=0 at ω=100 rad/s, a sinusoidal component exactly at 100 rad/s is ideally?

  • APassed unchanged
  • BCompletely rejected
  • CFrequency doubled
  • DConverted to DC
Report an error
Correct Answer: B. Completely rejected
Explanation: A zero frequency-response magnitude at that frequency means the corresponding sinusoidal steady-state component is suppressed.
Reference: Standard signals and systems: frequency response
Question 598
Signals & SystemsFilters

A band-pass filter is designed primarily to pass?

  • AA selected range of frequencies
  • BOnly DC
  • CAll frequencies equally
  • DOnly frequencies below zero
Report an error
Correct Answer: A. A selected range of frequencies
Explanation: A band-pass filter passes frequencies within a specified band while attenuating frequencies outside it.
Reference: Standard signals and systems: filters