Question

The output $Q_{n+1}$ of a J-K flip-flop for the input J =1, K=1 is

• A. 0
• B. 1
• C. $Q_n$
• D. ${\overline{Q}}_n$

Answer 1

The correct option is D ${\overline{Q}}_n$

The truth table of JK-FF is

$$\begin{array}{ccc}J& K& Q_{n+1}\\ 0& 0& Q_n\\ 0& 1& 0\\ 1& 0& 1\\ 1& 1& {\overline{Q}}_n\end{array}$$

for J=K =1
$Q_{n+1}={\overline{Q}}_n$
Hence option (d) is correct.