Question

Narrow, bright fringes are observed on a screen behind a diffraction grating. The entire experiment is then immersed in water. Do the fringes on the screen get closer together, get farther apart, remain the same, or disappear? Explain.

Answer 1

n (a sin θ) = m λ₀

n> 1, therefore the fringes move away from each other

Step-by-step 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