# Electronics and Communication Engineering - Signals and Systems

### Exercise :: Signals and Systems - Section 4

1.

If f(t) is in volts, then F(jω) is in

 A. volts B. volt seconds C. volts/sec D. volt-sec2

Explanation:

Since we integrate with respect to time to F(jω), we get volt-secs.

2.

A voltage V(t) which is a Gaussian ergodic random process with a mean of zero and a variance of 4 volt2 is measured by a true rms meter. The reading will be

 A. 0 B. 4 C. 2 D. 16

Explanation:

Rms Uvalue =4.

3.

Assertion (A): If , the final value of i(t) = 10

Reason (R): If , the initial value i(t) = 2

 A. Both A and R are correct and R is correct explanation of A B. Both A and R are correct but R is not correct explanation of A C. A is true, R is false D. A is false, R is true

Explanation:

Final value = 5. Hence A is wrong, initial value is 2. Hence R is correct.

4.

An ac circuit has an impedance of (3 + j6) ohm for fundamental. The impedance for fifth harmonic is

 A. (15 + j 30) Ω B. (15 + j 6) Ω C. (3 + j 30) Ω D. (3 + j 1.2) Ω

Explanation:

R is independent of w and XL ∝ ω.

5.

Which of following is recursive system?

 A. y(n - 1) B. y(n + 1) C. y(n) D. y(n) + y(n + 1)