Question

Find the angular separation between the consecutive bright fringes in a Young's double slit experiment with blue-green light of wavelength 500 nm. The separation between the slits is \[2 \cdot 0 \times  {10}^{- 3}m.\]

Answer 1

Given

Wavelength of the blue-green light,

\[\lambda = 500 \times  {10}^{- 9}   m\]

Separation between two slits,

\[d = 2 \times  {10}^{- 3}   m,\]

Let angular separation between the consecutive bright fringes be θ.

Using  \[\theta = \frac{\beta}{D} = \frac{\lambda D}{dD} = \frac{\lambda}{d},\] we get

\[          \theta = \frac{500 \times {10}^{- 9}}{2 \times {10}^{- 3}}\]

\[               = 250 \times  {10}^{- 6} \]

\[               = 25 \times  {10}^{- 5}\text{ radian or }0.014^\circ\]

Hence, the angular separation between the consecutive bright fringes is 0.014 degree.