We will determine the wavelength through the relationship given by the distance between slits, this relationship is given under the function

Here,
m = Number of order bright fringe
= Wavelength
d = Distance between slits
Both distance are the same, then



Rearranging to find the second wavelength




Therefore the wavelength of the light coming from the second monochromatic light source is 550.3nm
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It's called buoyancy. It is the tendency of an object to float