Flip-Flops and Timers Questions and Answers

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Flip-Flops and Timers are fundamental electronic components used in sequential logic circuits, and they often appear in logical reasoning questions and answers for competitive exams like ISRO, DRDO, and BARC. Understanding SR, JK, D, and T flip-flops helps in analyzing digital circuits’ state transitions. Timers such as the 555 IC are vital for pulse generation and time delay operations. In reasoning-based technical assessments, questions on timing diagrams, truth tables, and circuit behavior test both your logical and analytical skills. By practicing reasoning questions for competitive exams, you strengthen your grasp of digital electronics fundamentals essential for placement success.

Flip-Flops and Timers

Showing 10 of 20 questions

1. Which of the following is correct for a gated D-type flip-flop?

  • The Q output is either SET or RESET as soon as the D input goes HIGH or LOW.
  • The output complement follows the input when enabled.
  • Only one of the inputs can be HIGH at a time.
  • The output toggles if one of the inputs is held HIGH.
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2. When both inputs of a J-K flip-flop cycle, the output will:

  • be invalid
  • not change
  • change
  • toggle
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3. Latches constructed with NOR and NAND gates tend to remain in the latched condition due to which configuration feature?

  • asynchronous operation
  • low input voltages
  • gate impedance
  • cross coupling
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4. A basic S-R flip-flop can be constructed by cross-coupling which basic logic gates?

  • AND or OR gates
  • XOR or XNOR gates
  • NOR or NAND gates
  • AND or NOR gates
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5. One example of the use of an S-R flip-flop is as a(n):

  • transition pulse generator
  • astable oscillator
  • racer
  • switch debouncer
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6. If both inputs of an S-R NAND latch are LOW, what will happen to the output?

  • The output would become unpredictable.
  • The output will toggle.
  • The output will reset.
  • No change will occur in the output.
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7. An astable multivibrator is a circuit that:

  • has two stable states
  • is free-running
  • produces a continuous output signal
  • is free-running and produces a continuous output signal
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8. What is another name for a one-shot?

  • monostable
  • bistable
  • astable
  • tristable
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9. The truth table for an S-R flip-flop has how many VALID entries?

  • 3
  • 1
  • 4
  • 2
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10. What is the significance of the J and K terminals on the J-K flip-flop?

  • There is no known significance in their designations.
  • The J represents "jump," which is how the Q output reacts whenever the clock goes HIGH and the J input is also HIGH.
  • The letters represent the initials of Johnson and King, the co-inventors of the J-K flip-flop.
  • All of the other letters of the alphabet are already in use.
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