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Electronics and Communication Engineering - Exam Questions Papers

Exercise : Exam Questions Papers - Exam Paper 6
31.
The maximum effective aperture of an antenna which is operating at wavelength of 2 m and has a directivity of 100 is __________ .
15.92
31.84
3.184
1.592
Answer: Option
Explanation:

The maximum effective aperture is given by:

D = 100, λ = 2 m

.

32.
A speech signal, band limited to 4kHz and peak voltage varying between + 5V and - 5V is sampled at the Nyquist rate. Each sample is quantized and represented by 8 bits. Assuming the signal to be uniformly distributed between its peak values, the signal to noise ratio at the quantizer output is
156 dB
32 dB
48 dB
64 dB
Answer: Option
Explanation:

SNR = 6n + 1.7 = 6 x 8 + 1.7 = 48 + 1.7 .

33.
The drain current of a MOSFET in saturation is given by lp = K(VGS - VT)2 where K is a constant. The magnitude of the transconductance gm is
2K (VGS - VT)
Answer: Option
Explanation:

ID = k(VGS - VT)2,

.

34.
Two infinitely long wires carrying current are as shown in the figure below. One wire is in the y-z plane and parallel to the y-axis. The other wise is in the x-y plane and parallel to the x-axis. Which components of the resulting magnetic field are non-zero at the origin?
x, y, z components
x, y components
y, z components
x, z components
Answer: Option
Explanation:

Apply right hand thumb rule.

35.
A uniform plane wave is described by the equation H = A/m. If the velocity of the wave is 2 x 108 m/s and εr = 1.8, then. The electric field intensity is
90.35e-j0.1px v/m
903.5e-j0.1px v/m
903.5e-j0.1pz v/m
90.35e-j0.1pz v/m
Answer: Option
Explanation:

Using , we have,

∴

= 903.5e-j0.1pzv/m.

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