Wondering what to do with your overflowing recycling bin? This oh-so-cool DIY smart phone projector will inspire little engineers to turn recyclables into inventions. There’s no stopping the possibilities in a simple cardboard box!
To make our DIY smartphone projector, we grabbed:
- a small cardboard box (ours was 8 inches wide x 6 inches high x 12 inches long)
- a magnify glass or camera lens
- scissors, exacto knife, or small serrated knife
- a smart phone
Making the Projector
First, I had my 5 year old place the magnifying glass on the front of the box and trace it.
Then I used the scissors and a serrated paring knife to cut a hole in the box that was slightly smaller than the traced circle.
My 5 year old then used a spare piece of cardboard and folded it to make a stand for the phone. She secured it with a piece of tape.
She slid the phone stand into the box, under the a cardboard flap in the bottom of the box.
Next we taped the magnifying glass inside the box so that the lens aligned with the hole in the box.
Finally we added the smart phone on the stand.
My daughter immediately noticed that the movie was upside down. We fixed the problem by locking my phone onto landscape orientation. Then I placed the phone back in the projector, upside down this time.
I pointed the projector at a white wall and focused the picture by moving the phone away from or toward the lens until the picture looked clear.
When the picture was focused. I taped up the box, turned down the lights, and let the show begin.
The Science Behind It
How did the magnifying glass make the picture bigger? The answer is in the shape of the lens.
The lens is convex, meaning its sides bend outwards. This allows it to catch, bend, and focus all the light from inside the box and project it onto the wall.
But why is the image upside down?
The human eye has a lens similar to the magnifying glass attached to the projector. What the eye sees comes through the eye’s lens upside down but the brain learns to flip the image right side up. The magnifying lens flips the image through refracting the light from the phone’s screen just like your eye flips the light from the world.
Without a brain to flip the image for us, we have to set our phone in the box upside-down.
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