Question

In YDSE, the wavelength of light used is 6000Å. If path difference between waves reaching at a point P on screen is 1.5 microns, then at point P –

• A. Second bright exist
• B. Second dark exist
• C. Third dark exist
• D. Third bright exist

Answer 1

Answer: (C)

Third dark exist

Answer 2

Dx = (2n _ 1) $\frac{\lambda}{2}$ [for minima]

1.5 × 10^–6 = (2n – 1) × $\frac{6000 \times 10^{- 10}}{2}$

\ n = 3