When to use this calculator
Estimate ideal double-slit fringe spacing on a distant screen. Small-angle far-field approximation in air or vacuum with coherent illumination.
Explore the optics & quantum relationships calculators for other questions in this topic. For a related calculation, use the Carnot Efficiency Calculator: Find the Carnot thermal-efficiency limit from absolute reservoir temperatures.
PUTTING IT INTO PRACTICE
Young Double Slit Fringe: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Vacuum wavelength (nm) | 500 |
| Slit separation (mm) | 0.5 |
| Screen distance (m) | 2 |
| Result | 2 mm |
- Check the input labels and enter the example values above.
- Apply the relationship: Fringe spacing ≈ wavelength × screen distance/slit separation.
- The result is 2 mm, rounded for display.
How to interpret your result
Small-angle far-field approximation in air or vacuum with coherent illumination.
Use the stated sign convention for lenses and angles measured to the normal for refraction. Vacuum wavelength differs from wavelength inside a material. These models do not account for every optical aberration or material response.
Frequently asked questions
Why can a refracted-angle calculation have no real result?
When Snell’s-law sine exceeds one, the ideal ray model predicts total internal reflection rather than a real transmitted angle.
When is the young double slit fringe calculator useful?
Estimate ideal double-slit fringe spacing on a distant screen. Small-angle far-field approximation in air or vacuum with coherent illumination.
How do I use the young double slit fringe calculator?
Enter vacuum wavelength (nm), slit separation (mm), screen distance (m). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Fringe spacing ≈ wavelength × screen distance/slit separation.
What should I check before using the result?
Small-angle far-field approximation in air or vacuum with coherent illumination.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
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