For what distance is ray optics a good approximation when the aperture is `2 mm` wide and wavelength is `600 nm` ?

Explanation

To determine the distance at which ray optics is a good approximation given an aperture of 2 mm and a wavelength of 600 nm, we will use the concept of the Fresnel distance.

### Step-by-Step Solution:

1. **Identify the given values**:
- Aperture (a) = 2 mm = \(2 \times 10^{-3}\) m
- Wavelength (\(\lambda\)) = 600 nm = \(600 \times 10^{-9}\) m

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