YDSE — Fringe CountMediumQuestion 20231
Question
In YDSE (d = 0.5 mm, D = 1 m, λ = 500 nm), the number of complete fringes in 1 cm on the screen is:
- A10Correct
- B20
- C5
- D100
Correct answer
10
Explanation
β = λD/d = 500×10⁻⁹ × 1/0.5×10⁻³ = 10⁻³ m = 1 mm. Number of fringes in 1 cm = 10 mm / 1 mm = 10.