The Effect of Path Difference

Q. $S_1$ and $S_2$ are two coherent sources of sound of frequency $110\text{Hz}$ each and have no initial phase difference. The intensity at a point P due to $S_1$ is $I_0$ and due to $S_2$ is $4I_0$. If the velocity of sound is $330\text{m/s}$, then the resultant intensity at P is

1. $I_0$
2. $9I_0$
3. $3I_0$
4. $8I_0$

Q. A tuning fork having unknown frequency is sounded together with another tuning fork B of frequency $512H_Z$ 4 beats are heard. Now the tuning fork A is loaded with a little wax. The two forks are again sounded together. Now 5 beats are heard. What is the frequency of A?

1. 506 Hz
2. 507 Hz
3. 508 Hz
4. 509 Hz

Q.

When one of the slits in Young's experiment is covered with a transparent sheet of thickness $3.6\times {10}^{-3}$ cm the central fringe shifts to a position originally occupied by the 30th brigth fringe. If $\lambda =6000A,$ the refractive index of the sheet is

1. 1.5
2. 1.55

3. 1.60

4. 1.65

Q. Two tuning forks produce $4$ beats per second when they are sounded together. Now, both the forks are moved towards the observer at same speed $\left(u\right)$. The beat frequency now becomes $5\text{Hz}$. If the observer also begins to run with speed $u$ towards both the forks, what beat frequency will he hear now?

1. $8\text{Hz}$
2. $6\text{Hz}$
3. $4\text{Hz}$
4. $10\text{Hz}$