The amplitude of a wave represented by displacement equation $y = \frac{1}{{\sqrt a }}\,\sin \,\omega t \pm \frac{1}{{\sqrt b }}\,\cos \,\omega t$ will be
$\frac{{a + b}}{{ab}}$
$\frac{{\sqrt a + \sqrt b }}{{ab}}$
$\frac{{\sqrt a \pm \sqrt b }}{{ab}}$
$\sqrt {\frac{{a + b}}{{ab}}} $
The velocities of sound at the same pressure in two monatomic gases of densities ${\rho _1}$ and ${\rho _2}$ are $v_1$ and $v_2$ respectively. ${\rho _1}/{\rho _2} = 2$, then the value of $\frac{{{v_1}}}{{{v_2}}}$ is
A person speaking normally produces a sound intensity of $40\, dB$ at a distance of $1\, m$. If the threshold intensity for reasonable audibility is $20\,dB$, the maximum distance at which he can be heard clearly is ..... $m$
Two open organ pipes of fundamental frequencies $n_1$ and $n_2$ are joined in series. The fundamental frequency of the new pipe so obtained will be
A small source of sound moves on a circle as shown in the figure and an observer is standing on $O.$ Let $n_1,\, n_2$ and $n_3$ be the frequencies heard when the source is at $A, B$ and $C$ respectively. Then
Two pipes are each $50\,cm$ in length. One of them is closed at one end while the other is both ends. The speed of sound in air is $340\,ms^{-1}.$ The frequency at which both the pipes can resonate is