Question

Light of wavelength 675 nm passesthrough a double slit, and makes itsfirst minimum (m = 1) at an angle of0.111 deg. What is the separation ofthe slits, d, in MILLIMETERS?(Remember, milli means 10-3.)(Unit = mm)

Answer 1

wavelength = 675 nanometer

$\begin{gathered} \wedge=675nm \\ \text{Convert to mm} \\ \wedge=0.000675\operatorname{mm} \end{gathered}$

Therefore,

$\begin{gathered} d\sin 0.111=m\wedge \\ d=\frac{m\wedge}{\sin0.111} \\ d=\frac{1\times0.000675}{0.00193731425\times2} \\ d=\frac{0.000675}{0.00193731425\times2} \\ d=0.17421063226\operatorname{mm} \\ d=0.174\operatorname{mm} \end{gathered}$