Convert circuit to expression (3 marks)

Question: A logic circuit takes inputs A, B and C. Inputs A and B feed an OR gate. Input C is fed through a NOT gate. The two outputs feed an AND gate, producing output Q. Write the Boolean expression for Q and state the value of Q when A = 0, B = 1, C = 0.

Mark scheme (3 marks):

• 1 mark: (A OR B) correctly identified
• 1 mark: full expression Q = (A OR B) AND NOT C (accept (A + B).C̅ or (A ∨ B) ∧ ¬C)
• 1 mark: Q = 1 with working shown (A OR B = 1; NOT C = 1; 1 AND 1 = 1)
• Do not award the final mark for Q = 1 without supporting working/intermediate values.