A Young's double-slit experiment is performed using light that has a wavelength of 631 nm. The separation between the slits is 5.25E-5 m. Calculate the angle that locates the first-order bright fringes on the screen.

 θ = 1.21  10⁻² rad

Explanation:

The double slit experiment is described for constructive interference

           d sin θ = m λ

where d is the separation between the slits, λ the wavelength used, m a stereo that represents the order of interference

The first order of interference corresponds to m = 1 and the separation of the slits is d = 5.2 10⁻⁵ m

        sin θ = m λ / d

        θ = sin⁻¹ (m λ / d)

let's calculate

          θ = sin⁻¹ (1 631 10⁻⁹ / 5.2 10⁻⁵)

          θ = 1.21  10⁻² rad

pythagoras' theorem

square root (-5^2+9^2)

square root (25+81)

square root (106)

angle is tan^-1(9/5)

neg x, pos y