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Electronics and Communication Engineering - Exam Questions Papers

Exercise : Exam Questions Papers - Exam Paper 21
41.
It is required to match a 200 Ω load to a 450 Ω transmission line. To reduce the SWR along the line to 1, what must be the characteristic impedance of the quarter-wave transformer used for this purpose, if it is connected directly to the load?
90 kΩ
300 kΩ
Answer: Option
Explanation:
No answer description is available. Let's discuss.
42.
In an n-type silicon crystal at room temperature, which of the following can have a concentration of 4 x 1019 cm-3?
Silicon atoms
Holes
Dopant atoms
Valence electrons
Answer: Option
Explanation:
No answer description is available. Let's discuss.
43.
The reflection coefficient on a 500 m long transmission line has a phase angle of - 150°. If the operating wavelength is 150 m, what will be the number of voltage maxima on the line?
0
3
6
7
Answer: Option
Explanation:
No answer description is available. Let's discuss.
44.
Consider the following assertions
SI: For Zener effect at occur, a very abrupt junction is required
S2: For quantum tunnelling to occur, a very narrow energy barrier is required
Which of the following is correct?
Only S2 is true
SI and S2 are both true but S2 is not a reason for SI
SI and S2 are both true and S2 is a reason for SI
Both SI and S2 are false
Answer: Option
Explanation:
No answer description is available. Let's discuss.
45.
Given below a block diagram of oscillator circuit with various reactance elements.

For colpitts oscillator which is correct?
x1 = C, x2 = L, x3 = C
x1 = C, x2 = L, x3 = L
x1 = C, x2 = C, x3 = L
x1 = L, x2 = C, x3 = L
Answer: Option
Explanation:
No answer description is available. Let's discuss.
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