Answer:
As the string length got longer, wave frequency decreased
Step-by-step explanation:
Standing sound waves have the property similar to other waves in nature. The musical instrument like guitar, violin, etc works on the principle of standing sound waves.
The formula to find the frequency of standing waves is given by

Where,
f - frequency of the vibrating string
T - tension on the string
m - mass of the string
L - length of the string
According to this equation, when the length of the string is increased, the frequency of the wave decreases.