A beam of light of wavelength 400 nm falls on a narrow slit and the resulting diffraction pattern is observed on a screen 2 m away from the slit. It is observed that 2nd order minima occurs at a distance of 2 mm from the position of central maxima. Find the width of the slit.

Explanation

To find the width of the slit in the given diffraction problem, we will follow these steps:

### Step 1: Understand the given data
- Wavelength of light, \( \lambda = 400 \, \text{nm} = 400 \times 10^{-9} \, \text{m} \)
- Distance from the slit to the screen, \( D = 2 \, \text{m} \)
- Distance of the 2nd order minima from the central maxima, \( y = 2 \, \text{mm} = 2 \times 10^{-3} \, \text{m} \)

### Step 2: Relate the angle to the position of the minima
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