Electronics and Communication Engineering - Exam Questions Papers

Exercise :: Exam Questions Papers - Exam Paper 10

The transfer function Y(s)/R(s) of the system shown is

A.	0
B.
C.
D.

Answer: Option B

Explanation:

Construct a signal flow graph

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A lossless transmission line with air dielectric is 6 m long. What is the line length at 30 MHz?

A.	1 wavelength long
B.	0.5 wavelength long
C.	0.6 wavelength long
D.	0.25 wavelength long

Answer: Option C

Explanation:

V = 3 x 10⁸ m/s for lossless line

∴

∴ Line length = = 0.6 wave length long.

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Given that F(s) is the one-sided Laplace transform of f(t), the Laplace transform of f(t)dt is

A.	sFs - f(0)
B.
C.	F(t)dt
D.

Answer: Option B

Explanation:

Since it is one-sided Laplace transform.

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The antenna current of an AM broad cast transmitter, modulated to a depth of 40% by an audio sine wave is 11 amperes. It increased to 12 ampere as a result of simultaneous modulation by another sine wave. The modulation index due to this second sine wave is :

A.	0.4
B.	0.757
C.	0.643
D.	0.8

Answer: Option C

Explanation:

μ² = 0.57057, μ₁² + 0.16 = 0.57057

⇒ μ₁ = 0.64 .

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10.

Two D flip-flop as shown below are to be connected as a synchronous counter that goes through the following Q₁Q₀ sequence
00 → 01 → 11 → 10 → 00 → __________
The inputs D₀ and D₁ respectively should be connected as