# Signal Classification MCQ Quiz – Objective Question with Answer for Signal Classification

1. Which of the following is done to convert a continuous-time signal into a discrete-time signal?

A. Modulating
B. Sampling
C. Differentiating
D. Integrating

A discrete-time signal can be obtained from a continuous-time signal by replacing t with nT, where T is the reciprocal of the sampling rate or time interval between the adjacent values. This procedure is known as sampling.

2. The deflection voltage of an oscilloscope is a ‘deterministic’ signal.

A. True
B. False

The behavior of the signal is known and can be represented by a sawtooth waveform. So, the signal is deterministic.

3. The even part of a signal x(t) is?

A. x(t)+x(-t)
B. x(t)-x(-t)
C. (1/2)*(x(t)+x(-t))
D. (1/2)*(x(t)-x(-t))

Let x(t)=xe(t)+xo(t)
=>x(-t)=xe(-t)-xo(-t)
By adding the above two equations, we get
xe(t)=(1/2)*(x(t)+x(-t)).

4. Which of the following is the odd component of the signal x(t)=e(jt)?

A. cost
B. j*sint
C. j*cost
D. sint

Let x(t)=e(jt)
Now, xo(t)=(1/2)*(x(t)-x(-t))
=(1/2)*(e(jt) – e(-jt))
=(1/2)*(cost+jsint-cost+jsint)
=(1/2)*(2jsint)
=j*sint.

5. For a continuous time signal x(t) to be periodic with a period T, then x(t+mT) should be equal to ___________

A. x(-t)
B. x(mT)
C. x(mt)
D. x(t)

If a signal x(t) is said to be periodic with period T, then x(t+mT)=x(t) for all t and any integer m.

6. Let x1(t) and x2(t) be periodic signals with fundamental periods T1 and T2 respectively. Which of the following must be a rational number for x(t)=x1(t)+x2(t) to be periodic?

A. T1+T2
B. T1-T2
C. T1/T2
D. T1*T2

Let T be the period of the signal x(t)
=>x(t+T)=x1(t+mT1)+x2(t+nT2)
Thus, we must have
mT1=nT2=T
=>(T1/T2)=(k/m)= a rational number.

7. Let x1(t) and x2(t) be periodic signals with fundamental periods T1 and T2 respectively. Then the fundamental period of x(t)=x1(t)+x2(t) is?

A. LCM of T1 and T2
B. HCF of T1and T2
C. Product of T1 and T2
D. Ratio of T1 to T2

For the sum of x1(t) and x2(t) to be periodic the ratio of their periods should be a rational number, then the fundamental period is the LCM of T1 and T2.

8. All energy signals will have an average power of ___________

A. Infinite
B. Zero
C. Positive
D. Cannot be calculated

For any energy signal, the average power should be equal to 0 i.e., P=0.

9. x(t) or x(n) is defined to be an energy signal, if and only if the total energy content of the signal is a ___________

A. Finite quantity
B. Infinite
C. Zero
D. None of the mentioned

The energy signal should have a total energy value that lies between 0 and infinity.

10. What is the period of cos2t+sin3t?

A. pi
B. 2*pi
C. 3*pi
D. 4*pi