A parallel beam of light of `600 nm` falls on a narrow slit and the resulting diffraction pattern is observed on a screen `.12 m` away. It is observed that the first minimum is at a distance of `3 mm` from the centre of the screen. Calculate the width of the slit.

Explanation

To solve the problem, we will use the formula for the position of the minima in a single slit diffraction pattern. The position of the nth minimum is given by the formula:

\[ y_n = \frac{n \lambda D}{a} \]

where:
- \( y_n \) = position of the nth minimum from the center of the screen
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