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3 marksLogic Gates

CAPE Physics Unit 2 · 2011 · Paper 2 · Question 2(c)(iii)

A 1 kHz square wave of amplitude 5 V is input into one input of an XOR gate while the other input is grounded.

The same square wave is applied to one input of logic gate P while the other input is grounded. The output waveform is a flat line at 0 V. State the name of logic gate P and use a truth table to explain your answer.

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Other parts of this question

  1. 2(a)(i)What does the term 'bistable' mean when used in reference to an electronic circuit?[1 mark]
  2. 2(a)(ii)On Figure 2 (a), draw connecting wires to show the construction of an S-R flip-flop with inputs I_1 and I_2 and outputs Q and Q_bar. Complete the sequential…[5 marks]
  3. 2(b)Draw the truth table for the circuit using input waveforms A and B and resulting output waveform D shown in Figure 2 (b), and hence state the equivalent logic…[4 marks]
  4. 2(c)(i)What is the frequency of the XOR output?[1 mark]
  5. 2(c)(ii)If the same frequency is input but the other input to the XOR is tied to 5 V, what is the frequency of the output?[1 mark]

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