YDSE — Number of MaximaHardQuestion 20215
Question
In YDSE, the maximum order of the bright fringe that can be observed depends on:
- AScreen distance only
- BThe ratio d/λ — order n can be at most d/λCorrect
- CThe slit width only
- DThe source intensity
Correct answer
The ratio d/λ — order n can be at most d/λ
Explanation
Path difference = d sinθ. Maximum sinθ = 1 → maximum path difference = d. Maximum order: n_max = d/λ. For example, if d = 0.5 mm and λ = 500 nm: n_max = 0.5×10⁻³/500×10⁻⁹ = 1000.