A plane progressive wave cannot be represented by

1.  $\mathrm{y} = \mathrm{a} \sin \left(\mathrm{\omega t} \pm \mathrm{kx}\right)$

2.  $\mathrm{y} = \mathrm{a} \sin 2\mathrm{\pi }\left(\frac{\mathrm{t}}{\mathrm{T}}\mp \frac{\mathrm{x}}{\lambda }\right)$

3.  $\mathrm{y} = \mathrm{a} \sin \frac{2\mathrm{\pi }}{\mathrm{\lambda }} \left(\mathrm{Vt} \mp \mathrm{x}\right)$

4.  $\mathrm{y} = \mathrm{A} \log \mathrm{x} + \mathrm{B} \log \mathrm{x}$

The phase difference between the prongs of a tuning fork is :

1.  $2\mathrm{\pi }$

2.  $3\mathrm{\pi }$

3.  $\mathrm{\pi }$

4.  $5\mathrm{\pi }$

The isothermal elasticity of a medium is ${\mathrm{E}}_{\mathrm{i}}$ and the adiabatic elasticity in ${\mathrm{E}}_{\mathrm{a}}$. The velocity of sound in the medium is proportional to

1.  ${\mathrm{E}}_{\mathrm{i}}$

2.  ${\mathrm{E}}_{\mathrm{a}}$

3.  $\sqrt{{\mathrm{E}}_{\mathrm{i}}}$

4.  $\sqrt{{\mathrm{E}}_{\mathrm{a}}}$

When a wave is reflected from a denser medium the change in phase is :

1.  0

2.  $\mathrm{\pi }$

3.  $2\mathrm{\pi }$

4.  $3\mathrm{\pi }$

In a stationary wave along a string, the strain is:
1. zero at the antinodes
2. maximum at the antinodes
3. zero at the nodes
4. maximum at the nodes

A source of sound moves away with the velocity of sound from a stationary observer. The frequency of the sound heard by the observer:

1. remains the same

2. is doubled

3. is halved

4. becomes infinity
 

The longitudinal waves can travel :

1.  only in liquids

2.  only in solids

3.  only in gases

4.  In liquids, solids, and gases

The equation of a wave pulse travelling along x-axis is given by $y=\frac{30}{2+{\left(x-20t\right)}^2}$, x and y are in meters and t is in seconds. The amplitude of the wave pulse is 

1.  5 m

2.  20 m

3.  15 m

4.  30 m