TRB 2006 - Question 3

In a JK flipflop, $J=\bar Q$ and $K=1$. Assuming the flip flop was initially cleared and clocked for $6$ pulses, the sequence at the $Q$ will be

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a) $010000$ 
b) $011001$
c) $010010$
d) $010101$

Correct Answer: Option D

The characteristic equation of JK flip-flop is $$Q^+=J\bar{Q}+\bar{K}Q$$ Subs the given inputs, $J=\bar{Q}$ and $K=1$ $$Q^+=\bar{Q}\bar{Q}+0Q$$ $$Q^+=\bar{Q}+0$$ $$Q^+=\bar{Q}$$ From this we can say, for every clock pulse, the output of the JK flip-flop gets toggled. Hence $010101$ is the answer