Answer:
n (a sin θ) = m λ₀
n> 1, therefore the fringes move away from each other
Explanation:
The diffraction experiment the constructive interference fringes is described by
a sin θ = m λ₀
in this equation it is assumed that the experiment emptied the air n = 1
When the same experiment is performed in water, the wavelength changes
λₙ = λ₀ / n
execution for constructive interference
a sin θ = m λₙ
we substitute
a sin θ = m λ / n
n (a sin θ) = m λ₀
the refractive index of water is n = 1.33, so for the same wavelength the separation of the spectrum is multiplied by n> 1, therefore the fringes move away from each other
