# Why does refraction make something look closer with an incident angle of zero? [closed]

The gaussian formula for a single spherical surface is defined as

$$\frac{n}{s} + \frac{n'}{s'} = \frac{n'-n}{R}$$

When the radius of curvature, $R$, is infinite - as in the case of a planar surface, we are delt with the case

$$\frac{n}{s} = \frac{-n'}{s'}$$

and thus

$$s' = \frac{-sn'}{n}$$

Which means that if you look at an object in another medium with an incident angle of 0, the object may look closer or further away.

I understand why an object is not where "it seems" when looking into a different medium at an incident angle, but I dont understand why an object would appear farther or closer without and incident angle.

Why would an object appear farther or closer due to refraction when the incident angle is zero?