Digital Electronics MCQ Level- 1

QUESTION: 1

Figure-I shows a logic circuit with two inputs A and B and output C. The voltage incorrect waveform of A, B and C are shown in figure-II. The logic circuit is :

A.
NOR gate
B.
OR gate
C.
NAND gate
D.
AND gate

Solution:

From the waveform A, B and C, it is clear that output is 1, if both B and A are 1 otherwise zero.
C = A ^. B
The correct answer is: AND gate

QUESTION: 2

In Boolean Algebra, will be equal to.

A.
B.
C.
D.

Solution:

The correct answer is:

QUESTION: 3

When an input electrical signal A = 10100 is applied to a NOT gate, its output signal is :

A.
10100
B.
10101
C.
01011
D.
00101

Solution:

NOT gate implies output where A is the input.
The correct answer is: 01011

QUESTION: 4

The output Y from the following logic gate circuit will be :

A.
B.
C.
A + B
D.
A ^.B

Solution:

The correct answer is:

QUESTION: 5

The Boolean expression of the output Y in terms of the inputs A and B for the circuit shown in the following figure is.

A.
B.
C.
D.

Solution:

Equivalent circuit is

The correct answer is:

QUESTION: 6

The binary number 110000111101 corresponds to a hexadecimal number.

A.
CFD
B.
DBF
C.
D3C
D.
C3D

Solution:

Hexadecimal is written with 16 numbers starting from 0, i.e., 0, 1,2, 3,...14, 15. The number 10 → A; 11 → B; 12 → C; 13 → D; 14 → E; 15 → F in place of two digits. To convert binary number in hexadecimal make the pairs of four numbers starting from right. Then convert them in decimal then hexadecimal e.g. (110000111101)₂ ⇔ [(1100) (0011) (1101)₂] in binary number ⇔ [(12) (3) (13) ] in decimal
= C3D is the equivalent hexadecimal number
The correct answer is: C3D

QUESTION: 7

Figure I shows a two input type of logic circuit where A and B are the inputs and C is the output. The truth table of the logic gate is shown in Figure II.