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GUJCET · Physics · Wave Optics

Two slits are made \(\mathbf{1 0 ~ m m}\) apart and the screen is placed 1.5 m away. What is the fringe separation when wavelength of 7000 Å is used ?

  1. A \(105 \mu \mathrm{~m}\)
  2. B \(1.05 \mu \mathrm{~m}\)
  3. C \(10.5 \mu \mathrm{~m}\)
  4. D \(0.105 \mu \mathrm{~m}\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(105 \mu \mathrm{~m}\)

Step-by-step Solution

Detailed explanation

(A) \(105 \mu \mathrm{~m}\)
Fringe width
\(
\begin{aligned}
& \beta=\frac{\lambda \mathrm{D}}{d} \\
\therefore & \beta=\frac{7 \times 10^{-7} \times 1.5}{10 \times 10^{-3}} \\
\therefore & \beta=10.5 \times 10^{-5} \\
\therefore & \beta=105 \times 10^{-6} \mathrm{~m} \\
\therefore & \beta=105 \mu \mathrm{~m}
\end{aligned}
\)