Electronics and Communication Engineering - Exam Questions Papers

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?

A. 90 kΩ
B. 300 kΩ
C.
D.

Answer: Option B

Explanation:

No answer description available for this question. Let us 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?

A. Silicon atoms
B. Holes
C. Dopant atoms
D. Valence electrons

Answer: Option C

Explanation:

No answer description available for this question. Let us 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?

A. 0
B. 3
C. 6
D. 7

Answer: Option C

Explanation:

No answer description available for this question. Let us 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?

A. Only S2 is true
B. SI and S2 are both true but S2 is not a reason for SI
C. SI and S2 are both true and S2 is a reason for SI
D. Both SI and S2 are false

Answer: Option A

Explanation:

No answer description available for this question. Let us discuss.

45. 

Given below a block diagram of oscillator circuit with various reactance elements.

For colpitts oscillator which is correct?

A. x1 = C, x2 = L, x3 = C
B. x1 = C, x2 = L, x3 = L
C. x1 = C, x2 = C, x3 = L
D. x1 = L, x2 = C, x3 = L

Answer: Option C

Explanation:

No answer description available for this question. Let us discuss.