Question

A thin mica sheet of thickness $2 \times 10^{- 6}$m and refractive index (μ = 1.5) is introduced in the path of the first wave. The wavelength of the wave used is 5000Å. The central bright maximum will shift

• A. 2 fringes upward
• B. 2 fringes downward
• C. 10 fringes upward
• D. None of these

Answer 1

Answer: (A)

2 fringes upward

Answer 2

By using shift $\Delta x = \frac{p}{\lambda}(\mu - 1)t$

⇒ $\Delta x = \frac{\beta}{5000 \times 10^{- 10}}(1.5 - 1) \times 2 \times 10^{- 6} = 2\beta$

Since the sheet is placed in the path of the first wave, so shift will be 2 fringes upward.