Electronics and Communication Engineering - Exam Questions Papers

36.
Find the value of ix if each resistance is of 3 Ω and each battery is of 6 V.
1.1428 V
1.432 A
0.2892 A
O A
Answer: Option
Explanation:

Using Mesh analysis

Loop 1 : 6 = 9i1 - 3i4 ...(i)

Loop 2: 6 + 6 = - 6i2

i2 = - 2A ...(ii)

Loop 3: 6 = 9i3 - 3i4 ...(iii)

Loop 4: 6 = 9i4 - 3i3 - 3i1 ...(iv)

Solving the above equations simultaneously

i1 = i3 = 1.1428 A

i4 = 1.432 A

ix = i4 - i3 = 0.2892 A.


37.
An image uses 512 x 512 picture elements. Each of the picture elements can take any of the 8 distinguishable intensity levels. The maximum entropy in the above image will be
2097152 bits
786432 bits
648 bits
144 bits
Answer: Option
Explanation:

Picture elements (pixel) = 512 x 512 = 262144

Information per picture element N = log2 M

M = 2N

8 = 2N

N = 3

Information for 262144 pixels = 262144 x 3 = 786432 bits

Entropy is same as average information per message.


38.
Find RTH
200 Ω
0 Ω
400 Ω
None of these
Answer: Option
Explanation:

Since there is no independent source in the network

VTH = O V

To find RTh apply : A current source of 1 A across A and B.

Apply KCL at node n1

Apply KCL at node Vn2

Vn1 = 2Vx put in (i)

Vn2 = 4vx

put in (ii)

100 + Vx = 2Vx

100 = Vx

Vn2 = 4Vx = 400 V

.


39.
If then for this to be true x(t) is __________ .
exp (j2pf/t)
exp (-j2pf/t)
exp (j2pft)
exp (-j2pft)
Answer: Option
Explanation:

Consider x(t) = ej2pft

y(t) = h(t) * x (t)

y(t) = h(t). ej2pf(t - t) . dt

= ei2pfth(t) . e- j2pft . dt

= ej2pft x H(f) = x(t) x H(f)

.


40.
The dual transform of the given network as
none of the above
Answer: Option
Explanation:

Dual of R → G