GCE O-Level · Computing (7155)

Logic Gates: Practice Questions

5 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on Logic Gates.

10 questions20 marksFree, no account
Question 1
1 mark

Which logic gate provides a HIGH output (1) if and only if its two inputs are different?

Question 2
1 mark

A logic circuit has two inputs, \(A\) and \(B\). The output is given by the Boolean statement:
Output = \((A \text{ AND } B) \text{ OR } (\text{NOT } A)\)
What is the output when \(A = 1\) and \(B = 0\)?

Question 3
1 mark

Using De Morgan's Law and Boolean algebra properties, simplify the following Boolean expression:
\(\text{NOT } (A \cdot (B + \text{NOT } C))\)

Question 4
1 mark

According to De Morgan's theorem, the Boolean expression \(\overline{A \cdot B}\) is equivalent to which of the following?

Question 5
1 mark

Consider a 3-input logic system where the output \(Q\) is defined as \(Q = (A + B) \cdot \overline{C}\).
Which set of inputs will result in \(Q = 1\)?

Question 6
2 marks

State the output of a NOT logic gate when its input is 1.

Write your answer out first, then check it against the worked solution.

Question 7
3 marks

Using De Morgan's theorem, simplify the Boolean expression \( \text{NOT } (A \text{ AND } B) \) into an expression using OR and NOT operators.

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Question 8
2 marks

A logic circuit is represented by the Boolean statement \( P = \text{NOT } (A \text{ OR } B) \). Identify which single logic gate is equivalent to this statement.

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Question 9
4 marks

State the output of an AND logic gate when one input is 1 and the other input is 0.

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Question 10
4 marks

Consider the Boolean expression \(X = \overline{\overline{A} + \overline{B}} \cdot (\overline{A + B})\).


(a) Apply De Morgan\'s theorem to simplify the sub-expression \(\overline{\overline{A} + \overline{B}}\).
(b) Determine the fully simplified Boolean expression for \(X\).

Write your answer out first, then check it against the worked solution.

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