What happens if a light source would slowly decrease the wavelength from visible to nonvisible light?

Question

Ie if we had a light that could emit light from purple to UV. Do we see an instant change from purple to nothing or does it slowly fade out?

In: Physics

Answer 1

it would seem to fade. in fact, the apparent brightness of the light would change *dramatically* as it went through the spectrum because our sensitivity to certain wavelengths is highly varied.