How to use the double-slit interference calculator
Compute fringe spacing in Young's double slit experiment. Enter wavelength, slit separation, screen distance in the fields above; the fringe spacing is computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- lam — Wavelength (nm)
- d — Slit separation (mm)
- L — Screen distance (m)
Worked example
With wavelength = 550 nm, slit separation = 0.2 mm, screen distance = 1.5 m, the calculator gives fringe spacing ≈ 4.125 mm.
Frequently asked questions
What is the formula for the double-slit interference calculation?
Fringe spacing (mm) = lam × 1e-9 × L / (d × 1e-3) × 1000. Here lam is wavelength (nm), d is slit separation (mm), L is screen distance (m).
What inputs do I need for the double-slit interference calculator?
You need wavelength in nm, slit separation in mm, screen distance in m. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.