Switching Circuits and Logic Design: Week 3 : Assignment 3

1. Which of the following switching expression identities are true?

 a. A + (B.C) = (A + B).(A + C)

 b. A + A’.C.D = A + C.D

 c. A + B’.C.D = A + B’

 d. A.(A + B) = B

2. The dual of the switching expression (X + (Y . 1)) + (Z + 0) is

 a. (X.(Y + 0)).(Z . 1)

 b. (X.(Y + 1)).(Z . 0)

 c. (X + (Y + 0)).(Z + 1)

 d. None of these

3. Which of the following are false for switching expressions?

 a. If A + B = B + C + D, then A = C + D

 b. A.B + A’.C + B.C = A.B + A’.C

 c. (A + B + C)’ = A’.B’.C’

 d. (A + B + C)’ = A’+B’+C’

4. The switching expression F = X’.Y + Y’.Z’ + X.Y + Y’.Z after minimization becomes

 a. F = X + Y’

 b. F = X + Y

 c. F = 0

 d. F = 1

5. The switching expression (A.B + A’.B’)’ in sum-of-products form is

 a. A.B + A’.B’

 b. A.B’ + A’.B

 c. A’B’ + A’B + A’B

 d. None of these

6. Three managers have a key of a safe with them, and it requires any two keys to open the safe. If A, B and C denote the presence of the three managers respectively in front of the safe, write down the switching expression denoting the condition for opening the safe?

 a. A.B + B.C + C.A

 b. (A + B + C) . (A’ + B’ + C’)

 c. A.B + B.C + C.A + A.B.C

 d. All of these

7. For the function F = A’.B + A.C, the set of all true minterms are

 a. A’.B, A.C

 b. A’.B.C’, A’.B.C, A.B’.C, A.B.C

 c. A’.B, A.C, A’.B.C’, A’.B.C, A.B’.C, A.B.C

 d. None of these

8. For the functions F1 = A.B + B.C’ + C’.D, F2 = A.C.D + B.D, F3 = A’, which of the following are true?

 a. F1 is unate, F2 is positive unate, F3 is negative unate

 b. F1 and F3 are negative unate, F2 is positive unate

 c. F1 is non-unate, F2 is positive unate, F3 is negative unate

 d. None of these

Ans: a

9. How many 2-input NAND gates will re required in minimum to realize the function F = A’.B + C.D? ……………….

Ans: 4

10. Which of the following are functionally complete sets?

 a. AND, OR, NOT

 b. NAND, NOT

 c. EXOR, 1

 d. AND, EXOR, 0