Exam-style question
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A circuit has three inputs, A, B and C. A is connected to a NOT gate. The output of that NOT gate and B are connected to an OR gate. The output of the OR gate and C are connected to an AND gate. Write the Boolean expression for the final output and complete the output for A = 1, B = 0 and C = 1.
Model answer
What a good answer should say
- The Boolean expression is ((NOT A) OR B) AND C.
- For A = 1, NOT A = 0.
- Then 0 OR B, where B = 0, gives 0.
- Finally, 0 AND C, where C = 1, gives a final output of 0.
Explanation
Why this works
The expression follows the circuit from left to right: first invert A, then OR that result with B, and finally AND the result with C. Evaluating each intermediate output prevents the connections between gates from being confused.
Common mistake
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