Answer:
1.5106 cm
Step-by-step explanation:
The beat frequency is equal to the absolute value of the difference between the frequencies of the two signals:

using the wave equation, we can re-write each frequency as

where c is the speed of light and
is the wavelength. Therefore,

where:
is the beat frequency
is the wavelength of the first generator
is the wavelength of the second generator
We also know that the second generator emits the longer wavelength, so we already know that the term inside the module is positive. Therefore, we can now solve for
:
