Electronics and Communication Engineering - Exam Questions Papers

Exercise :: Exam Questions Papers - Exam Paper 8

P_x(X) = M exp(- 2 |x|) + N exp(- 3 |x|) is the probability density function for the real random variable X, over the entire x axis. M and N are both positive real numbers. The equation relating M and N is

A.
B.
C.	M + N = 1
D.	M + N = 3

Answer: Option A

Explanation:

Using property of probability density of P_xdx = 1

[M exp(- 2 |x|) + N exp(- 3|x|)]dx

1 ⇒ .

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The electric field component of a time harmonic plane EM wave travelling in a non magnetic lossless dielectric medium has an amplitude of 1 V/m. If the relative permittivity of the medium is 4, the magnitude of the time-average power density vector (in W/m²) is

A.
B.
C.
D.

Answer: Option C

Explanation:

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The open loop transfer function of a unity feedback control system is given as The phase cross over frequency and the gain margin are respectively.

A.	and
B.	and
C.	and
D.	and

Answer: Option A

Explanation:

At phase cross over frequency

-90° - tan^{- 1} ωT₁ - tan^{- 1} ω_cT₂ = - p

= 90°

GM = 1/a where a = | G(jω)|_{ω=ω_c}

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A unity negative feedback closed loop system has a plant with the transfer function and a controller G_c(S) in the feed forward path. For a unit set input, the transfer function of the controller that gives minimum steady state error is