1. Which signal is said to be power signal?
a) Finite power and zero energy
b) Finite power and infinite energy
c) Infinite power and non-zero energy
d) Infinite power and zero energy
Explanation: A signal is said to be power signal if it has finite power and infinite energy.
2. Find the fundamental period of 1+sin2(3π/5)n.
a) 5
b) 3π/5
c) 10/3
d) None of the above
Explanation: sin2(3π/5)n = (1-cos(6π/5)n)/2 = 1/2-1/2cos(6π/5)n
period = 6π/(5*2π) = k/N = 3/5
N=5
3. A unit impulse function has?
a) Unity weight
b) Large amplitude
c) Zero pulse width
d) All of the above
Explanation: An impulse function has infinite or large amplitude, zero pulse width and unity weight which is concentrated at zero.
4. Which signal is called as energy signal?
a) Finite energy and zero power
b) Infinite energy and zero power
c) Finite energy and non-zero power
d) Infinite energy and non-zero power
Explanation: A signal is said to be an energy signal if it has finite energy and zero average power.
5. Determine the periodicity and also find whether it is a power or energy signal?
e(-at)u(t)
a) Periodic and energy signal
b) Periodic and power signal
c) Non periodic and energy signal
d) None of the above
Explanation: This is non periodic as it does not repeat itself after any period. And on calculating we will get energy as 1/2a which is finite. Thus it is an energy signal.
6. What is the period of a signal x(t)?
a) 2T
b) T
c) T/2
d) None of the above
Explanation: A signal is said to be periodic if the duration of one complete cycle is T and it repeats itself after this duration.
7. Discrete impulse signal is a power or energy signal?
a) Energy signal
b) Power signal
c) Both power and energy signal
d) Neither power nor energy signal
Explanation: On calculating using energy formula we will get the energy of this signal as 1 which is a finite value. Thus it is a energy signal.
8. Check whether the signal is periodic or not?
x(t) = cos(4t) + 2sin(8t)
a) Periodic with period 2
b) Periodic with period 2/π
c) Periodic with period π/2
d) Not periodic
Explanation: T1=2π /4 T2=2π /8, T1/T2 = 2 T=T1 or 2T2, T=π /2
9. Which of the given signals are periodic?
a) x(t) = 4u(t) + 2sin(3t)
b) x[n] = 2sin(3n)
c) x(t) = u(t) – 1/2
d) x(t) = 4 cos(5πt)
Explanation: T=2π / 5π = 2/5, periodic with period 2/5
10. Continuous Impulse signal is a power or energy signal?
a) Energy signal
b) Power signal
c) Both power and energy signal
d) Neither power nor energy signal
Explanation: On calculating using the power and energy calculation formula we will arrive at it is neither power nor energy signal.