Gardening and mirrors

You could also call this one " reflected light" - cuz I want to ask 2 very related questions yet unique unto themselves.

The first one has to do with my garden-project for my wife- she needs a greenhouse so that the animals won’t eat her … creations hehe.

The problem comes up when I’m looking for a good sunny spot… yup… slim to none, but there are some areas, just not any good to build anything ontop of. So I had to wonder - can a mirror give a plant the same …eh… “nutrients” what the sun’s rays could do directly?

Next on the docket is another mirror question, this time pertaining to headlights. I’ve been talking with some folks on my usual car forum about headlight modding and the re’s a a part inside every headlamp called a “shield” … now what I wanted to know is… How is it that blocking portions of a bulb’s radiated light can actually “focus” light… how exactly does bl;ocking light , make it more intense?

Thanks ahead of time

It is possible to use a mirror to reflect sunlight onto plants and they will certainly appreciated it; there are losses involved, as no mirror is a perfect reflector, but they can probably be ignored. However, I think it may be a little ambitious to be hoping to illuminate an entire greenhouse with mirrors; you’ll need quite a big array of them to catch and redirect enough light and if you’ve got the space for that, arguably you should just build the grrenhouse in that location instead.

On the headlamp thing, is it not the case that the back of the shield (that is the side facing the filament) is silvered, so that it reflects light back toward the main reflector?

Thanks for taking another one of my “fabulous” querues to the masses on MT.
In regards to the greenhouse, you’ve told me all I need to know- how things happen is my challenge and no I’m not this ambitious if you’re wondering ;).

The 2nd more difficult Q (in my opinion) is a hard one for me to even explain, being as I only have what I’ve learned via forum perusing tonight to even describe what I am asking.

MT- since you’re the only “taker” on this so far- the shield in many cases I believe is reflective, but in my case it is not since I have my headlamps opened-up on the floor behind me. It’s not even a reflective metal color; just a dull 3-D gray box-shaped apendage with something close to a target circle cut-out of the front where the light would pass through. At the dead-center this “target circle” is what appears to be a “dot” as to obstruct light in that tiny region (the very-center)

Sorry to do this, but you know what “Target” store logos look like right? That’s it to a “t” just mentally cut-away the white parts in the logo and leave the red ones… I hope this makes sense- just trying to lend a visual aid that’s universally identifiable… anyway the principal seems to be the same with a mag-lite flashlight also only you are positioning the bulb to focus the light, where as I believe the way my headlight works is bouncing light around inside to come out focused… only I don’t understand how and why blocking certain parts of the light radiated from the bulb can actually “focus” the light beam or even make it appear brighter… :confused:

What you’re talking about is known (among people who deal with optics regularly) as a zone plate (or sometimes a Fresnel zone plate); it works through constructive interference of light waves. I’d try to explicate it further, but optics was never my strong suit in college physics; at least I’ve given you something to Google on. :slight_smile: