BEE Digital Circuits 3

Question 1

What is the primary advantage of using Gray code in shaft encoders compared to standard binary code?

Accepted Answer

Only one bit changes between consecutive values

Answer

Gray code is designed so that consecutive values differ by exactly one bit, eliminating transition errors when multiple bits would otherwise change simultaneously.

Question 2

Which Boolean expression is correctly simplified using De Morgan's theorem: NOT(A AND B)?

Accepted Answer

NOT(A) OR NOT(B)

Answer

De Morgan's theorem states that NOT(A·B) = NOT(A) + NOT(B), converting NAND to OR of complements.

Question 3

A 4-to-1 multiplexer has select lines S1 and S0 with S1=1, S0=0. Which input is routed to the output?

Accepted Answer

I2

Answer

With S1=1 and S0=0, the binary select value is 10₂ = 2, so input I2 is selected.

Question 4

What is the output of a D flip-flop on the rising clock edge when D=0 and the current state Q=1?

Accepted Answer

Q becomes 0

Answer

A D flip-flop samples D on the active clock edge and transfers it directly to Q, so Q becomes 0 regardless of the previous state.

Question 5

In a Karnaugh map for a 3-variable function, a group of four 1-cells eliminates how many variables?

Accepted Answer

2

Answer

Each doubling of the group size (1→2→4→8) eliminates one additional variable, so a group of 4 eliminates 2 variables from the expression.

BEE - Bachelor of Electrical Engineering Practice Test

BEE - Bachelor of Electrical Engineering Practice Test

BEE Digital Circuits 3