67. AQA GCSE (8525) SLR11 – 3.4 Boolean expressions

What does the NOT gate do?

• Reverses the input

• Combines two inputs where both have to be true

• Combines two inputs where at least one has to be true

• Combines two inputs where exactly one has to be true

Answer explanation

The NOT gate reverses the input, making a true input false and a false input true.

What is required for an AND gate's output to be true?

• Both inputs are true

• Exactly one input is true

• At least one input is true

• Both inputs are false

Answer explanation

For an AND gate's output to be true, both inputs must be true. This is because the AND gate only outputs true when both inputs are true.

How is the OR gate symbolized in Boolean algebra notation?

• +

• A plus symbol with a circle around it

• A / bar above the section

• .

Answer explanation

The OR gate is symbolized in Boolean algebra notation by the plus symbol (+).

What is the correct Boolean expression for a NOT gate applied to input C?

• NOT(C)

• C OR NOT

• C AND NOT

• NOT C

Answer explanation

The correct Boolean expression for a NOT gate applied to input C is NOT(C), which represents the negation of input C.

In the given examples, how is the output labeled?

• D

• C

• B

• A

Answer explanation

The correct answer is D because in the examples provided, the output is labeled alphabetically, starting from D.

Which gate requires only one input to be true and the other to be false for the output to be true?

• AND gate

• OR gate

• XOR gate

• NOT gate

Answer explanation

The XOR gate requires only one input to be true and the other to be false for the output to be true, making it the correct choice.

How is the AND gate represented in text format?

• +

• A / bar above the section

• A plus symbol with a circle around it

• .

Answer explanation

The AND gate is represented in text format as a period or dot symbol, which is the correct answer choice in this question.

What is the Boolean expression for the output of an AND gate with inputs A and B?

• A + B

• A XOR B

• A . B

• NOT A AND B

Answer explanation

The correct Boolean expression for the output of an AND gate with inputs A and B is A . B, which represents the logical AND operation between A and B.

Which Boolean operator is represented by a plus symbol with a circle around it?

• AND

• NOT

• XOR

• OR

Answer explanation

The Boolean operator represented by a plus symbol with a circle around it is XOR, which stands for exclusive OR. It is used to indicate that either one condition or the other is true, but not both.

What is the Boolean expression for the output D, which equals A AND B OR NOT C?

• D = A XOR B AND NOT C

• D = A . B + NOT C

• D = NOT A AND B OR C

• D = A + B OR NOT C

Answer explanation

The correct Boolean expression for D is A . B + NOT C, which represents A AND B OR NOT C. Therefore, the correct answer is D = A . B + NOT C.