Answer:
When n = 1,
f1 = v/2L
This is known as the fundamental frequency.
When n = 2,
f2 = 2(v/2L)
This is known as the first overtone.
When n = 3,
f3 = 3(v/2L)
This is known as the second overtone.
When n = 4,
f4 = 4(v/2L)
This is known as the third overtone.
The tone is always the same as the fundamental frequency.