The fundamental frequency of a closed pipe is 400 Hz . If $\left(\frac{1}{3}\right)^{\text {rd }}$ length of the pipe is filled with water, the frequency of the $2^{\text {nd }}$ harmonic of the pipe will be (Neglect end correction)

To get output of the following logic circuit as ' 0 ' (zero), the inputs $A, B, C$ should NOT be, respectively,

The displacement of particle in S.H.M. is $\mathrm{x}=\mathrm{A} \cos (\omega \mathrm{t}+\pi / 6)$. Its speed will be maximum at time $\left(\sin 90^{\circ}=1\right)$

The power factor of a CR circuit is $\frac{1}{\sqrt{2}}$, If the frequency of a.c. signal is halved, then the power factor of the circuit will become