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 at which ray optics is a good approximation given an aperture of 3 mm and a wavelength of 500 nm, we can use the concept of Fresnel Distance. Here’s the step-by-step solution:

### Step 1: Understand the concept of Fresnel Distance
Fresnel Distance (Z_f) is the minimum distance that light can travel before showing wave properties. If the distance is less than the Fresnel Distance, ray optics can be considered a good approximation.

### Step 2: Use the formula for Fresnel Distance
The formula for Fresnel Distance is given by:
\[ Z_f = \frac{A^2}{\lambda} \]
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