For what distance is ray optics a good approximation when the aperture is 3 mm wide and the wavelength is 500 nm ?

Explanation

To determine the distance for which ray optics is a good approximation given an aperture width of 3 mm and a wavelength of 500 nm, we will use the concept of Fresnel Distance (Zf). The Fresnel Distance indicates the minimum distance a ray of light can travel before it starts to exhibit wave-like properties, such as diffraction.

### Step-by-Step Solution:

1. **Identify the Parameters:**
- Aperture width (a) = 3 mm = \(3 \times 10^{-3}\) m
- Wavelength (λ) = 500 nm = \(500 \times 10^{-9}\) m = \(5 \times 10^{-7}\) m

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