31. Stationary waves of frequency 300 Hz are formed in a medium in which the velocity of sound is 1200 m/s. The distance between a node and the neighbouring anti node is

1. 1. 1 m

   
   
   

   2. 2 m

   
   
   

   3. 3 m

   
   
   

   4. 4 m

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

---

32. What is the frequency of a wave whose time-period is 0.05 second ?

1. 1. 5 Hz

   
   
   

   2. 10 Hz

   
   
   

   3. 20 Hz

   
   
   

   4. 40 Hz

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

---

---

33. A string 1 m long is drawn by a vibrator attached to its end. The string vibrates in three segments. If the frequency of vibration of the vibrator is 480 Hz, then what is the speed of waves through the string ?

1. 1. 160 Hz

   
   
   

   2. 320 Hz

   
   
   

   3. 480 Hz

   
   
   

   4. 640 Hz

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

---

34. How does the speed V of sound in air depend on atmospheric pressure P ?

1. 1. V ∝ P^-1

   
   
   

   2. V ∝ P²

   
   
   

   3. V ∝ P⁰

   
   
   

   4. V ∝ P^1/2

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

---

---

35. When two sound waves are superimposed, beats are produced when they have

1. 1. Different amplitudes and phases

   
   
   

   2. Different velocities

   
   
   

   3. Different phases

   
   
   

   4. Different frequencies

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

---