Quiz: Logic Gates

A logic circuit outputs HIGH only when all three inputs A, B, and C are HIGH. Which gate combination can achieve this if only NAND gates are available?

• One NAND gate

• Two NAND gates in cascade

• Three NAND gates with feedback

• Four NAND gates configured as AND equivalent

Which Boolean expression represents a circuit that activates a relay only when at least two of three sensors (A, B, C) are ON?

• AB+BC+ACAB + BC + ACAB+BC+AC

• A+B+CA + B + CA+B+C

• ABACABAC

• A'B'+BC'+A'C'A'B' + BC' + A'C'A'B'+BC'+A'C'

If a NOR gate’s inputs are both tied together and connected to signal A, what is the resulting output function?

• A

• A’

• 0

• 1

A system alarm turns ON (logic 1) if the temperature sensor is active (T=1) and either smoke (S=1) or motion (M=1) is detected. What is the Boolean expression?

• T(S+M)T(S + M)T(S+M)

• T+SMT + SMT+SM

• (T+S)M(T + S)M(T+S)M

• TS+MTS + MTS+M

Simplify the Boolean expression Y=A'B+AB'/+ABY = A'B + AB' + ABY=A'B+AB'+AB.

• A+BA + BA+B

• A⊕BA \oplus BA⊕B

• A+B'A' + B'A+B'

• A+B'+ABA + B' + ABA+B'+AB

Which logic gate’s output is LOW only when all inputs are HIGH?

• A. AND

• B. OR

• C. NAND

• D. NOR

In a 4-input AND gate, what is the probability of getting a HIGH output if each input has a 0.5 probability of being HIGH?

• 0.5

• 0.0625

• 0.25

• 0.125

A fault causes the output of an XOR gate to behave like an OR gate. Which type of failure most likely occurred?

• Input shorted to ground

• Output stuck-at-1 fault

• Missing inverter at output

• Cross-connection between inputs

A combinational circuit is defined as Y=(A+B’)(C+D). For A=0,B=1,C=1,D=0, what is Y?

• 0

• 1

• Undefined

• Oscillating

If the Boolean function F(A,B,C)=Σ(1,3,5,7), what simplified expression does it represent?

• A. A'+CA' + CA'+C

• B. B+CB + CB+C

• C. A+BA + BA+B

• D. B⊕CB ⊕plus CB⊕C