Question

In a JK flip-flop the J input is connected to 0 and its K input is connected to output Q. A clock pulse is fed to the clock input. The flip-flop will now:

• A. Change its state for each clock input
• B. Goes to state 1 and remains at 1
• C. Goes to state 0 and remains at 0
• D. Retains the previous state

Hint:

In JK flip-flop, J = 0 means no setting possible — so it retains the current state if K = Q.

Answer 1

The Correct Option is D

Step 1: JK Flip-Flop Basics
The JK flip-flop is a universal flip-flop with inputs J (Set), K (Reset), Clock, and Output Q. The behavior is as follows:
J = 0, K = 0 $\Rightarrow$ No change (retains previous state)
J = 0, K = 1 $\Rightarrow$ Reset (Q = 0)
J = 1, K = 0 $\Rightarrow$ Set (Q = 1)
J = 1, K = 1 $\Rightarrow$ Toggle
Step 2: Given Configuration
Here:
- J = 0 (fixed)
- K = Q (feedback from output)
- Clock pulse is applied
Since J = 0 and K = Q (either 0 or 1), the input condition becomes J = 0 and K = something. Regardless of K, if J = 0, the flip-flop cannot be set or toggled.
Step 3: Resulting Operation
According to JK behavior: when J = 0 and K = any value, the output retains its previous state.
Conclusion:
JK Flip-Flop holds its state when J = 0 regardless of K — Option (4) is correct.