# EC8392 Important Questions Digital Electronics

## Sample EC8392 Important Questions Digital Electronics:

1. State Demorgan’s Theorem.
De Morgan suggested two theorems that form important part of Boolean algebra. They are,
i. The complement of a product is equal to the sum of the complements.
(AB)’ = A’ + B’
ii. The complement of a sum term is equal to the product of the complements.
(A + B)’ = A’B’ EC8392 Important Questions Digital Electronics

2. Implement using NAND gates only, F = x y z + x′ y′.

3. What are Don’t care terms? In some logic circuits certain input conditions never occur, therefore the corresponding output never appears. In such cases the output level is not defined, it can be either high or low. These output levels are indicated by ‘X’ or ‘d’ in the truth tables and are called don’t care conditions or incompletely specified functions. EC8392 Important Questions Digital Electronics

4. Apply De-Morgan’s theorem to [ (A+B) + C ] ′. Given [(A+B)+C] ′ = (A+B) ′.C′
= (A′.B′).C′
[(A+B)+C] ′ = A′B′C′

5. Convert 0.35 to equivalent hexadecimal number.
Given (0.35)10 =0.35 x 16=5.60 =0.60 x 16=9.60 =0.60 x 16=9.60 (0.35)10 = (0.599)16 EC8392 Important Questions Digital Electronics

6. Convert Y=A+BC′+AB+A′BC into canonical form.
Given Y=A+BC′+AB+A′BC Y=A(B+B′)(C+C′)+(A+A′)BC′+AB(C+C′)+A′BC Y=ABC+ABC′+AB′C+AB′C′+ABC′+A′BC′+ABC+ABC′+A′BC Y=ABC+ABC′+AB′C+AB′C′+A′BC′+A′BC

7. Define ‘min term’ and ‘max term’.
A product term containing all the variables of the function in either complemented or uncomplemented form is called a min term. A sum term containing all the variables of the function in either complemented or uncomplemented form is called a max term. EC8392 Important Questions Digital Electronics

8. Prove that the logical sum of all min terms of a Boolean function of 2 variables is 1.
Consider two variables as A and B. For two variables A and B minterms are: A′B′,A′B,AB′,AB. The logical sum of these minterms are given by F= A′B′+A′B+AB′+AB = A′(B′+B)+A(B′+B) (B′+B=1) = A′(1)+A(1) (A′+A=1) F=1 Hence it is to be proved. EC8392 Important Questions Digital Electronics

 Subject name Digital Electronics Semester 3 Subject Code EC8392 Regulation 2017 regulation