Question
Question: Wavelength if its speed is 320 m/sec, are – 
A
8 cm, 400 Hz
B
80 cm, 40 Hz
C
8 cm, 4000 Hz
D
40 cm, 8000 Hz
Answer
8 cm, 4000 Hz
Explanation
Solution
2.5l = 20 cm, l = 8 cm.
n = 
= 4000 Hz.