What is sound level for intensity of 10^–6 W/m²?

1. 50 dB 

2. 60 dB

3. 70 dB 

4. 80 dB

A : The propagation of sound in air should be an isothermal process.

R : As air is bad conductor of heat, its temperature does not change by compression or expansion.

Given below are two statements:

A source of sound placed at the open end of a resonance column sends an acoustic wave of pressure amplitude ${\rho }_0$ inside the tube. If the atmospheric pressure is ${\rho }_A$ , then the ratio of maximum and minimum pressure at the closed end of the tube will be :

1. $\frac{({\rho }_A+{\rho }_0)}{({\rho }_A-{\rho }_0)}$

2. $\frac{({\rho }_A+2{\rho }_0)}{({\rho }_A-2{\rho }_0)}$

3. $\frac{{\rho }_A}{{\rho }_A}$

4. $\frac{\left({\rho }_A+\frac{1}{2}{\rho }_0\right)}{\left({\rho }_A-\frac{1}{2}{\rho }_0\right)}$

Which one of the following statements is true?

The time of reverberation of a room \(A\) is one second. What will be the time (in seconds) of reverberation of a room, having all the dimensions double those of room A?

1. 2

2. 4

3. $\frac{1}{2}$

4. 1

A transverse wave propagating along the \(x\text-\)axis is represented by:
\(y(x,t)=8.0\sin\left(0.5\pi x-4\pi t-\frac{\pi}{4}\right)\), where \(x\) is in meters and \(t\) in seconds. The speed of the wave is: 
1. \(4\pi\) m/s
2. \(0.5\) m/s
3. \(\frac{\pi}{4}\) m/s
4. \(8\) m/s

Two sound waves with wavelengths \(5.0~\text{m}\) and \(5.5~\text{m}\), respectively, propagate in gas with a velocity of \(330~\text{m/s}\). How many beats per second can we expect?
1. \(12\)
2. \(0\)
3. \(1\)
4. \(6\)