We have some low energy lights positioned on the top of our kitchen wall cupboards. If I placed mirrors under them would that increase the illuminatoion.
It would have the effect of increasing the illumination by redirecting or "bouncing" the light that was heading downwards towards the (presumably) dark kitchen cupboards which would dull the illumniation. Those redirected light rays would join the original rays heading upwards increasing it's intensity.
Bear in mind that it doesn't increase the intensity of the eminating light from the bulb, it only redirects it.