Logic Gates
1. Which of the following statements is true about an AND gate?
a) Outputs 1 only if one of the inputs is 1.
b) Outputs 1 only if both inputs are 1.
c) Outputs 1 if at least one input is 0.
d) Outputs the same value as both its inputs.
Answer: b) Outputs 1 only if both inputs are 1.
Explanation: An AND gate only outputs a HIGH (1) when both of its inputs are HIGH (1).
2. What is the output of a NOT gate with an input of 0?
a) 0
b) 1
c) Depends on the specific NOT gate.
d) Undefined.
Answer: b) 1
Explanation: A NOT gate inverts the input. So, if the input is 0, the output will be 1 (opposite of the input).
3. The truth table for an OR gate shows:
a) Output is 1 only when both inputs are 1.
b) Output is 1 only when one input is 1.
c) Output is 0 only when both inputs are 0.
d) Output is always 1.
Answer: b) Output is 1 only when one input is 1.
Explanation: An OR gate outputs a HIGH (1) if at least one of its inputs is HIGH (1).
4. What is the output of an XOR gate when both inputs are 0?
a) 0
b) 1
c) Cannot be determined.
d) Depends on the specific XOR gate.
Answer: b) 1
Explanation: An XOR gate outputs 1 when the number of 1s in the inputs is odd. Since both inputs are 0 (even), the output is 1.
5. Which gate is represented by the Boolean expression A + ¬A?
a) AND
b) OR
c) XOR
d) NAND
Answer: c) XOR
Explanation: A + ¬A translates to A OR NOT(A), which is the expression for an XOR gate.
6. Which of the following statements is NOT true about a NAND gate?
a) It is a combination of an AND gate and a NOT gate.
b) Its output is the opposite of an AND operation.
c) It can be used to implement any other logic gate.
d) Its output is 1 only when both inputs are 1.
Answer: d) Its output is 1 only when both inputs are 1.
Explanation: A NAND gate outputs 0 only when both inputs are 1, making it the opposite of an AND operation.
7. What is the output of a NOR gate if one of its inputs is 0?
a) 0
b) 1
c) Cannot be determined.
d) Depends on the specific NOR gate.
Answer: b) 1
Explanation: A NOR gate outputs 1 only when both of its inputs are 0. So, if one input is 0, the output will be 1 regardless of the other input.
8. Which gate's output is always the opposite of the input?
a) AND
b) OR
c) XOR
d) NOT
Answer: d) NOT
Explanation: A NOT gate's sole purpose is to invert the input signal.
9. What is the symbol for an AND gate?
a) ∨
b) ⊕
c) ¬
d) ⋅
Answer: d) ⋅
Explanation: This symbol, resembling a dot, represents the AND operation.
10. Which Boolean expression represents an OR gate with inputs A and B?
a) A ⋅ B
b) A + B
c) A ⊕ B
d) ¬A ∧ ¬B
Answer: b) A + B
Explanation: The "+" symbol in Boolean expressions represents the OR operation.