Answer:
500Hertz
Step-by-step explanation:
Given the fundamental frequency of the string given as 1.25x10²Hz
Harmonics are integral multiples of the fundamental frequency.
In strings, the third harmonic F3 is expressed in terms of the fundamental frequency expressed as;
F3 = 4F0
F0 is the fundamental frequency;
Given
F0 = 1.25x10²Hz
F3 = 4(1.25x10²)
F3 = 4(125)
F3 = 500Hz
Hence the frequency of the third harmonic is 500Hertz