Electronics and Communication Engineering - Exam Questions Papers

6. 

The depth of penetration at 4 MHz is 10 cm, then at 2.5 MHz it is

A. 62.5 cm
B. 13 cm
C. 6.25 cm
D. 8 cm

Answer: Option B

Explanation:

Depth of penetration

δ2 = 12.64 cm.


7. 

The expression given is F(A, B , C, D, E, F, G, H) = (33, 48, 102, 158, 222, 229, 233, 243, 255); then the __________ and __________ minterms are grouped together into dual and variable __________ is reduced using the dual

A. 243, 233, D
B. 222, 158, B
C. 243, 255, A
D. 229, 243, E

Answer: Option B

Explanation:

We use Quine - McCluskey method of reduction :

We can observe that minterms 158 and 222 can be grouped together to reduce the variable 'B'.


8. 

Calculate i(t) for t ≥ 0 assuming the switch has been in position A for a long time. At t = 0, the switch is moved to position B.

A.
B.
C.
D.

Answer: Option D

Explanation:


9. 

A source produces 4 symbols with probabilities , , , For this source, a practical coding scheme has an average codeword length of 2 bits/symbol. The efficiency of the code is

A. 1
B.
C.
D.

Answer: Option B

Explanation:

Total information for L message is

Efficiency =.


10. 

A generator of 50 Ω internal impedance and operating at 1 GHz feeds a 75 Ω load via a coaxial line of characteristic impedance 50 Ω. The VSWR on the feed line is

A. 0.5
B. 1.5
C. 2.5
D. 1.75

Answer: Option B

Explanation:

ZL = 75 Ω

Zo = 50 Ω

Reflection coefficient:

.