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Electronics and Communication Engineering - Signals and Systems

Exercise : Signals and Systems - Section 3
36.
A voltage wave is i = 100 sin (ωt). Its average value calculated over one half cycle is
zero
70.72 V
63.70 V
none of the above
Answer: Option
Explanation:

.

37.
In the given figure 15.5 show a discrete time system consisting of a unit delay system, a multiplier and a summer, such that y(k) = x(k - 1) + 0.5 x(k). This system
is linear
is non linear
may be linear or non linear depending on value
impossible to judge
Answer: Option
Explanation:

All the elements are linear.

38.
An RLC series circuit has a variable inductance. The value of L for resonance conditions at fundamental frequency is 0.18 H. For resonance conditions at third harmonic frequency the value of inductance is
0.54 H
0.06 H
0.02 H
1.62 H
Answer: Option
Explanation:

.

39.
which of the following is not correct?
P(A) = P(A) - 1
0 ≤ P ≤ 1
If A and B are mitual exclusive then P(A + B) = P(A) + P(B)
P(A) = 1 - P(A)
Answer: Option
Explanation:

P(A) + P(B) = 1.

40.
If function f(t) has an initial value f(0-) at t = 0-, the Laplace transform of is
sF(s) - f(0-)
sF(s) + f(0-)
s2F(s) - f(0-)
s2F(s) + f(0-)
Answer: Option
Explanation:

£f(t) =

£-1F(s) = f(t)

£[a f1(t) + bf2(t)] = aF1(s) + bF2(s)

where

£[f(t - T)] = e-sT F(s)

£[e-at f(t)] = F(s + a)

Initial value theorem

Final value theroem

Convolution Integral

where t is dummy variable for t.

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