Electronics and Communication Engineering - Signals and Systems

1. 

If f(t) is in volts, then F(jω) is in

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

Answer: Option B

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

Answer: Option C

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

Answer: Option D

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

Answer: Option C

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)

Answer: Option A

Explanation:

In Recursive system, Present output depend upon past.


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