Electronics and Communication Engineering - Signals and Systems

36. 

The signal defined by the equations f(t) = 0 for t < 0, f(t) = E for 0 ≤ ta and f(t) = 0 for t > a is

A. a step function
B. a pulse function
C. a shifted step function originating at t = a
D. none of the above

Answer: Option B

Explanation:

It is a pulse lasting for t = a.


37. 

Inverse Laplace transform of is

A. 2 exp (- 2.5 t) cosh (0.5 t)
B. exp (- 2 t) + exp (- 3 t)
C. 2 exp (- 2.5 t) sinh (0.5 t)
D. 2 exp (- 2.5 t) cos 0.5 t

Answer: Option B

Explanation:

f(t) = e-2t + e-3t.


38. 

Two function g1(t) and g2(t) with correlation of 6 has average power of 4 and 5 respectively. The power of g1(t) + g2(t) is

A. 9
B. 21
C. 3
D. 15

Answer: Option B

Explanation:

Power of two correlated signal is P = P1 + P2 +2R1, 2(t).


39. 

A box has 4 white and 3 red balls. Two balls are taken out in succession. What is the probability that both are white?

A.
B.
C.
D.

Answer: Option C

Explanation:

The probability that first ball is white is and the probability the second ball is white is . The probability that both are white is .


40. 

Z transform is a non-linear operation.

A. True
B. False

Answer: Option B

Explanation:

Z transform is a linear operation.