Signals and Systems – Multiple Choice Questions (MCQs)

1. 1. Which of the following is a continuous-time signal?

   • A. x[n] = cos(nπ/4)
   • B. x(t) = e^(-t)
   • C. x[n] = u[n]
   • D. x[n] = δ[n]

2. 2. A signal is periodic if:

   • A. x(t) = x(t + T) for some T > 0
   • B. x(t) = x(-t)
   • C. x(t) = 0 for t < 0
   • D. ∫|x(t)|^2 dt < ∞

3. 3. Which of the following is an even signal?

   • A. sin(t)
   • B. cos(t)
   • C. e^t
   • D. u(t)

4. 4. A system is linear if it satisfies:

   • A. Homogeneity property
   • B. Additivity property
   • C. Both homogeneity and additivity
   • D. Time-invariance

5. 5. A system is time-invariant if a time shift in the input causes:

   • A. No change in output
   • B. The same time shift in the output
   • C. A phase shift in the output
   • D. A change in amplitude of the output

6. 6. Which of the following describes a causal system?

   • A. Output depends on future inputs
   • B. Output depends on past and present inputs
   • C. Output depends on future outputs
   • D. Output depends only on present input

7. 7. A stable system is one where:

   • A. Bounded input produces bounded output
   • B. Unbounded input produces bounded output
   • C. Bounded input produces unbounded output
   • D. Output goes to infinity

8. 8. The Fourier Series represents a periodic signal as a sum of:

   • A. Sinusoids
   • B. Exponentials
   • C. Impulses
   • D. Ramp functions

9. 9. The Fourier Transform of a constant signal x(t) = A is:

   • A. Aδ(ω)
   • B. 2πAδ(ω)
   • C. A/jω
   • D. A

10. 10. What is the Fourier Transform of the unit impulse function δ(t)?:

    • A. 1
    • B. ω
    • C. jω
    • D. 2πδ(ω)

11. 11. The convolution of two signals in the time domain corresponds to ________ in the frequency domain.

    • A. Multiplication
    • B. Division
    • C. Addition
    • D. Subtraction

12. 12. The Laplace Transform of a unit step function u(t) is:

    • A. 1
    • B. 1/s
    • C. s
    • D. e^-s