Answer:
2.6m
Step-by-step explanation:
The formula for calculating the wavelength is expressed as;
λ = v/f
v is the velocity
f is the frequency of vibration
Given
f = 7.80Hz
We need to get the velocity
For string;
f = V/2L
7.80 = V/2(1.3)
7.80 = V/2.6
V = 2.6 * 7.8
V = 20.28m/s
Get the required wavelength
λ = v/f
λ = 20.28/7.80
λ = 2.6m
Hence the wavelength of the first harmonic is 2.6m