Electronics and Communication Engineering - Exam Questions Papers

16.
If 137 + 276 = 435 how much is 731 + 672?
534
1403
1623
1513
Answer: Option
Explanation:

Given, 137 + 276 = 435

Adding units digits i.e., 7 + 6 = 13, but given as 5, which is 13 - 8 and also 1 is carry forwarded to the tens digit.

i.e., + 1

Here, 7 + 3 + 1 = 1 i.e., 11 - 8 = 3 and 1 is carry forwarded to hundred digits

Now, the sum of digits in hundred's place is 1 + 1 + 2 = 4

ie.,

Using the same logic, we have

Using digits sum 1 + 2 = 3

Tens digits sum = 3 + 7 = 10

i.e., 10 - 2 and + 1 carry forward Hundreds digits sum = 1 + 7 + 6 = 14

i.e., 14 - 8 = 6 and one carry forward.


17.
An astable multivibrator circuit using IC 555 timer is shown below. Assume that the circuit is oscillating steadily

The voltage Vc across capacitor varies between
3 V to 5 V
3 V to 6 V
3.6 V to 6 V
3.6 V to 5 V
Answer: Option
Explanation:

Charging and discharging level of capacitor will be the voltage across it.

This is equal to Vcc and Vcc.

Thus 3V to 6V is the voltage VC across the capacitor.


18.
The fourier transform of a double sided exponential function
is
Answer: Option
Explanation:

Consider general expression

X(jω) = ea|t| e- jωt dt

= eat e-jωt dt + e-ate-jωt dt

X(jω) = e(a - jω)t dt + e -(a + jω)t dt

Since .


19.
The number of product terms in the minimized sum of product expression obtained through the following k map is (where "d" denotes don't care states)
2
3
4
5
Answer: Option
Explanation:

Y = A B D + A B D + A C D.


20.
If A = then |A50| will be
(1 - 1002)
(1 - 502)
(1 - 1002)
(1 - 502)
Answer: Option
Explanation:

An = ?

Every n x n matrix satisfy its characteristic equation |A - λI| = 0 λ -> eigen vector

A - λI =

|A - λI| = = 0

1 =,

f(A) = An = β0I + β1A

Replace A by 1, I by 1

f(λ) = λn = β0 + β1λ

Differentiate w.r.t. λ nλn - 1 = β1

β1 =

β0 = λn - β x λ

β1 =

β0 = - = [1 - n]

An = [1 - n]+ . 2n

An =

=

A50 =

|A50| = (1 - 502).