Constants Light of wavelength 640 nm falls on two slits and produces an interference pattern in which the third-order bright red fringe is 46 mm from the central fringe on a screen 2.6 m away. What is the separation of the two slits?

Express your answer to two significant figures and include the appropriate units.

1.1 * 10⁻⁴ m = 0.11 mm

Explanation:

d y / L = m λ is the formula that relates the slit separation with all other given quantities here.

y = fringe width = 46 mm = 0.046 m

L = distance to the screen = 2.6 m

Wavelength = λ = 640 nm

Order of the fringe = m = 3

Slit separation = d = m λL / y = (3) (640 * 10⁻⁹) (2.6) / 0.046

= 1.1 * 10⁻⁴ m = 0.11 mm