Problem — Young's fringes

Problem

In a Young’s experiment, light of wavelength $600\;\text{nm}$ passes through two slits separated by $0{,}20\;\text{mm}$. The screen is at $1{,}0\;\text{m}$. Calculate the distance between two consecutive bright fringes.

Solution

Setup. In the double slit, the distance between consecutive fringes is $\Delta y = \dfrac{\lambda D}{d}$, with $\lambda = 600\cdot 10^{-9}\;\text{m}$, $d = 0{,}20\cdot 10^{-3}\;\text{m}$, $D = 1{,}0\;\text{m}$:

$\Delta y = \frac{\lambda D}{d} = \frac{600\cdot 10^{-9}\cdot 1{,}0}{0{,}20\cdot 10^{-3}} = \frac{6{,}0\cdot 10^{-7}}{2{,}0\cdot 10^{-4}}$

$\Delta y = 3{,}0\cdot 10^{-3}\;\mathrm{m} = \ev{3{,}0\;\mathrm{mm}}$

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Topics: Ottica Concepts: Interferenza