Question 7
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Figure 3 is the switching arrangement of a logic circuit.
Complete Table 1 using Figure 3 by stating condition of output lamp (F) either as on or off
S1 S2 S3 Output (F) open open open open open Close open Close open open Close Close Close open open Close open Close Close Close open Close Close Close - Write the Boolean expression for the output (F) in terms of the inputs S1, S2 and S3.
Observation
The Chief Examiner reported that only a few candidates obtained full marks in this question. It was also reported that some candidates described the output as ‘open’ and ‘close’ contrary to the instruction of ‘on’ or ‘off’ in the question.
The expected responses were:
(b). Boolean expression
(S1.S2 ) + S3 = F