The minimum intensity of sound is zero at a point due to two sources of nearly equal frequencies, when :

1. Two sources are vibrating in opposite phase

2. The amplitude of the two sources are equal

3. At the point of observation, the amplitudes of two S.H.M. produced by two sources are equal and both the S.H.M. are along the same straight line

4. Both the sources are in the same phase

Two sound waves (expressed in CGS units) given by $y_1=0.3\sin \frac{2\pi }{\lambda }(vt-x)$ and $y_2=0.4\sin \frac{2\pi }{\lambda }(vt-x+\theta )$ interfere. The resultant amplitude at a place where the phase difference is π/2 will be :

(1) 0.7 cm

(2) 0.1 cm

(3) 0.5 cm

(4) $\frac{1}{10}\sqrt{7}cm$

If two waves having amplitudes 2A and A and same frequency and velocity, propagate in the same direction in the same phase, the resulting amplitude will be 

1. 3A

2. $\sqrt{5}A$

3. $\sqrt{2}A$

4.  A

The intensity ratio of the two waves is 1 : 16. The ratio of their amplitudes is 

(1) 1 : 16

(2) 1 : 4

(3) 4 : 1

(4) 2 : 1

The superposing waves are represented by the following equations : $y_1=5\sin 2\pi (10t-0.1x)$, $y_2=10\sin 2\pi (20t-0.2x)$ Ratio of intensities $\frac{I_{\max }}{I_{\min }}$ will be :

(1) 1

(2) 9

(3) 4

(4) 16

The displacement of a particle is given by $x=3\sin \left(5\pi t\right)+4\cos \left(5\pi t\right)$. The amplitude of the particle is :

(1) 3

(2) 4

(3) 5

(4) 7

The two interfering waves have intensities in the ratio 9 : 4. The ratio of intensities of maxima and minima in the interference pattern will be :

(1) 1 : 25

(2) 25 : 1

(3) 9 : 4

(4) 4 : 9

If the ratio of amplitude of two waves is 4 : 3. Then the ratio of maximum and minimum intensity will be :

(1) 16 : 18

(2) 18 : 16

(3) 49 : 1

(4) 1 : 49

Equation of motion in the same direction is given by $y_1=A\sin (\omega t-kx)$, $y_2=A\sin (\omega t-kx-\theta )$. The amplitude of the medium particle will be 

1. $2A\cos \frac{\theta }{2}$

2. $2A\cos \theta$

3. $\sqrt{2}A\cos \frac{\theta }{2}$

4. $1.2f,1.2\lambda$

The displacement of the interfering light waves are $y_1=4\sin \omega t$ and $y_2=3\sin \left(\omega t+\frac{{\displaystyle \pi }}{{\displaystyle 2}}\right)$. What is the amplitude of the resultant wave :

(1) 5

(2) 7

(3) 1

(4) 0