MCQs on Digital Electronics

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01․ In the toggle mode a JK flip-flop has
J = 0, K = 0.
J = 1, K = 1.
J = 0, K = 1.
J = 1, K = 0.

J = 0, K = 0; no change condition between pre-state and next state. J = 0, K = 1; it is always reset condition means next state is always 0. J = 1, K = 0; it is always set condition means next state is always 1. J = 1, K = 1; it is toggle condition means when pre-state is 1 then next state is 0 or when pre-state is 0 then next state is 1.
02․ A three-state buffer has the following output states
1, 0, float
High, Low, Float
Both A and B
Set, Reset, Halt

A three-state buffer when enabled output is HIGH and is LOW when disabled. And neither of these condition, then it will be in FLOAT state.
03․ Which of the following is a digital device
Regulator of a fan
Microphone
Resistance of a material
Light switch

A light switch has two condition. ON and OFF, which is similar to that of digital conditions 1 and 0 which is the basic of Boolean algebra. Rest have Fuzzy logic.
04․ A Binary number system has how many digits.
0
1
2
10

A binary number system consists of only ONE and ZERO or can be stated as High and Low means it has only two digits.
05․ If a Hexadecimal number needs to convert to binary. For each hexadecimal digit, there will be how many bits
1
2
4
8

Hexadecimal number system is a base-16 number system ( 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F ). As F can be represented using 4 bits (1 1 1 1), So for each hexadecimal digit one need 4 bits.
06․ Temperature variation is a/an
Digital quantity
Analog quantity
Either Digital or Analog quantity
None

Temperature variation is not a discrete quantity respect to time. It is continuous w.r.t time. So its an analog quantity.
07․ In Digital Logic Designs, GAL is abbreviated as
General Advance Logic
General Array Logic
Generic Advance Logic
Generic Array Logic

GAL is Generic Array Logic. It is a re programmable device used in Digital Systems.
08․ In decimal number system what is MSD
First digit from left to right
First digit from right to left
Middle digit
Mean of all digits

MSD means Most Significant Digit. It is represented by the first digit from left to right, it has the highest weight-age out of all. It can also represent the signed or unsigned number.
09․ A digital circuit that can store on bit is a
XOR gate
flip-flop
gate
registor

A flip-flip is the basic unit for storing digital data and it can store only one bit.
10․ Stack is also known as
FIFO memory
Flash memory
LIFO memory
LILO memory

Stack is a type of memory based on Last In First Out. A data stored last will be read first.
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